Well I went from a 180 (4'x3') w/55 gal sump to a 375 (6'x5') w/270g sump , and bigger was most definitely not better. Due to the added size the thickness of the acrylic impacted which pumps I could use, I had 5 Vortech MP40s + 1 MP60 on the 180, the 375 I ended up using cheaper pumps that I could put a heftier magnet on.
The added size also had issues with actual water flow, counting up the GPH of the pumps in the tank I was pushing somewhere in the range of 15-20k GPH, but it just wasn't quite right. It was like there was too much flow near the pump, but it peetered out far away, so my idea of doing a peninsula changed to a 2 sided tank, to a screw it I'm putting pumps on all 4 sides and damn the looks. I do acknowledge there the the geometry of the tank (wasn't long and skinny) definitely had something to do with it.
Larger tank means more maintenance, there's zero ways around it too, quickly found out that 40G brute I used for water changes on the 180 was no where near as useful. So I got a 100G water container, and ended up having a saltwater reserve there. And while water changes were better, it brought a whole new slew of issues, need to change filters on my RO/DI unit that much more. And yeah the cost of it does add into things.
I'm of the mindset that more volume does not mean more stability after a certain point, of course this is going to differ based on certain issues each person has. I view more volume as a larger boat, sure it can hold off bad things for a while, but if something goes unchecked you're trying to do a tight turn with the Titanic to avoid that iceberg... just ain't going to happen. So back to water changes, if you need to do 2 50% water changes in a hurry to fix something*(whatever that is) it's easier to do with a smaller system, with a larger system you need to have that system in place to do that, which I did not.
Electricity... from larger area to light, to larger volume of water I need to keep at 80F when the ambient is closer to 60F, yeah it adds up in a hurry
Cleaning... so 3 sides viewable eh? Acrylic eh? You better make sure you can pencil in an appointment every week to clean off 22 square feet of acrylic, because if it builds up, then get overwhelmed in a hurry. Of course YMMV on this.
So overall I'm not saying things couldn't have been better, it's just very easy to not be prepared for a larger tank. And it can quickly overwhelm you, and then it's like a rising tide of trying to catch up with it.
That said, 180 vs 240 isn't a huge difference in size as far as needing to get on top of it, and nothing says you NEED a bigger sump either. Enough to hold your equipment, enough to catch all the water in case of a power outage.