How very cool - I remember doing all of my pool sessions - in fact, I still hit the pool from time to time to get a "perfect environment" where the water is clear and warm and there's no current... It's a great place to dip in and practice skills, nail weighting, and even introduce others to scuba. Congratulations on everything you've accomplished thus far - hope you're having a blast playing with the gear and the new dimension that you now have control over - up and down.
I know Henderson suits pretty well - in fact, I know suits in general pretty well. On average we probably purchase one every one to two months, between me (and my work, which tears them up), Kym and any other diver we've got working with us.
My experience with Hendersons is that they really stress the super-soft, stretchy neoprene that's a relative newcomer in the wetsuit market. That's their "niche." It makes for a very comfortable suit, because it stretches over your body for a perfect fit and gives when you move, preventing binding.
The downside to super-stretchy neoprene is that it crushes with depth moreso than typical neoprene... So your 3 mil at the surface becomes a 1 mil at 60 feet, where it's colder anyway.
Neoprene isn't a very good material to make a dive suit from - it's very buoyant because of all of the trapped air bubbles inside of the suit (which is the reason it insulates, so it's not like it can be designed out). It also crushes at depth, meaning it gets thinner the deeper you go. At 30 feet, your typical wetsuit is half as thick as it is on the surface, and at 60 feet it's about 1/3 as thick... Of course, reducing it's ability to insulate you from the cold. Also because of this buoyancy, you'll have to compensate by wearing more weight - and the thicker the suit, the more weight you'll have to wear.
...Assuming you're correctly weighted at the surface, all things equal, you'll therefore be too heavy at depth, because your suit has crushed. You'll find that you can compensate by adding air to your bc or bp/wing.
...Which of course, means that you'll be too light as you ascend and your suit re-expands. Again, you can compensate by letting air out of your bc or bp/wing.
With a 3 mil suit (thin), the amount of air you have to add at depth and release at the surface isn't much - but the thicker the suit, the more you have to compensate... Which is why really thick suits suck, but are sometimes necessary if the water's really that chilly, and you don't have a drysuit (which has valves in it so that you can compensate the suit right within the suit).
Herein starts the process of "gear sucks" - which is why I recommend adopting an early philosophy of "don't buy it unless you absolutely have to in order to dive." Suits - you absolutely need them to dive... Diving outside the pool environment, there's all kinds of stinging, sharp marine nasties, to say nothing of the chill - so yes, absolutely wear a suit... But minimize it. Wear minimally thick suits so that you aren't constantly compensating, you can minimize your weight, and have a more enjoyable dive overall. Thinner suits also have the advantage that they're more comfortable, won't bind at your joints, and cost less and can be replaced for less when the one you have gets hosed up or wears out.
Okay - back to the Henderson - that super-stretchy neoprene tends to wear out faster than the old stiffer stuff. It also compresses quicker at depth, meaning that it'll offer less thermal protection than the old stiffer stuff. A better design is their latest stuff, which has soft, stretchy flexible panels where it's needed, and less stretchy neoprene where it's not needed.
Henderson has, over the past decade or so, relied on their super-stretchy neoprene design to give the diver a good fit, which their suits do, at least when they're new and on the surface. Now that super-stretchy neoprene is no longer a Henderson-only feature (it's been around long enough to be adopted by other wetsuit manufacturers), frankly, I've found other suits that are both less pricey and a better fit.
My personal favorites are the Sector series of dive suits made by O'Neill - O'Neill is arguably the company that invented the wetsuit, and for decades made them with the material available at the time - thick, stiff neoprene. To get a good fit, they had to create a suit that was anatomically correct - curved in all of the right places. As such, you'll never find a straight seam on an O'Neill... All of the seams are curved around the body, because the body is a series of curves, not straight lines. Consequently, they have a fantastic fit - always have. Now that they've adopted the super-stretchy neoprene for key areas, their suits fit better than ever, are exceedingly comfortable, nearly keep the diver dry inside (reducing the water flow inside the suit is the key to making a high quality, warm wetsuit), and last longer than any suit we've tried. We highly recommend them.
Unfortunately, you'll be hard-pressed to find O'Neill suits in dive shops... Henderson, Scubapro and Akona are much more common, with Pinnacle starting to make a name for itself in the market. All of these suits have straight seams, and therefore require stretchier neoprene to give a good fit, which is sometimes questionable anyway.
In practical terms, if you choose a super-stretchy suit, you'll have to get a thicker suit to have the same amount of thermal protection - which of course, means more weight... And a more difficult time maintaining buoyancy... And so the cycle of clusterf**k begins.
...So yeah, Henderson is a good suit - but for less money you can get a better fitting, more comfortable, drier inside, warmer, less-affected-by-depth suit from O'Neill. They're just tough to find.
...Which is why we buy all of our suits from Dennis at Austin's Diving Center in Miami, Florida. He's "on the ball" and has a great stock of O'Neill dive suits. They're at
http://www.austinsdiving.com . Tell them SeaJay sent you and I'm sure he'll hook you up with a great deal.