Hi John:
Thanks for the question.
I'm not sure its a better design, its just different. It does add a few new features which someone might like, especially if they are trying to pull the maximum skimming out of their beckettheaded skimmer.
So what it does over the shorter bullet box style skimmer, it provides tangental injection, and that swirling water pattern which effectively increases contact time. The Xl also can use slightly weaker pumps as bubble inconsistancies don't directly effect the foam settling -althou more powerful pumps really make this skimmer rock. The aerofoamers has been using this tangental injection scheme and people really seem to like it. The downside is, the large XL doesn't fit under many cabinents. Also you have to clean the whole reaction column.
So now your left w/ a piece of furntiture which sits outside your stand and makes whooshing noises
Yes I have touched the XL. (actually I have the prototypes of this model as well-maybe next months article =^0) I would consider this skimmer to be in the same category as any of the aerofoamers, and the MTC 1000.
Another thing which I'm hoping PM will start incorportating is a screw -top beckett containment chamber. I have griped repeatedly about trying to clean the becketthead.
Either the Xl style or bullet box style skimmers kick major booty, they are considered pricey, but honestly once you touch one of his products you understand why. Thick plastics, seamless welds, 1/4 thick flanges, nylon screws, and spears gate valves.
Anything specifically you'd like me to comment on?
Thanks
frank