Did you choose a tank?!?
[For what it’s worth] I got a Reefer 250 6 months ago knowing in a few years (3-5 I said, ha) I’d want to upgrade to a larger (& more expensive
525XL or 650 Peninsula. I was proud of myself for being “conservative.” That said, I’m already looking at upgrading (and I’m certain I will before Christmas) I’m a bit worried I’ll over stock my tank (admittedly I’m impulsive) before I can upgrade... and that’s not even accounting for coral/amimal growth (that I far underestimated) ��...
I went small for two reasons: financially of course (initially the tank was less expensive), and, because I couldn’t decide where exactly I’d put the tank in my home (different locations for different size/style tanks).
Financially, the difference in initial tank purchase (small vs large/r) tank may seem large ($750 difference in your example) though in the big picture is nominal. The capital outlay of all the added ‘things’ (lights, pumps, skimmer, etc) is very similar regardless of what size tank you get (e.g. Vertex Skimmer 130 is $319 & 150 is $399... either way you’re spending $3XX+); things like a Neptune Apex ($799) is the same price regardless of the size tank you put it on, same for the ATO system (reservoir cost may vary with size +/-$50). Overall one could be all-in on a Reefer 250 $4000 and a similarly equipped 450 $5000... for that kind of money, get the one you LOVE (and that’s probably the larger one
So my two-cents is go larger if you’re comfortable with the space / fit in your home. I’ve never read a posting where someone said “I should have gotten the 180, the 220 is just too big.”