The main problem I've had is being able to move these big tanks to the room they are going to. It is a logistical nightmare to setting them up. Just getting my current tank which is "only" a 190 cube from the garage to the room in setting it up in took 5 guys (and $300 for them)
I have a simple view on this, tank first, fish later.
Why buy a fish when your tank is too small, then have to go out buy another tank? Decide on what you want to keep, get the proper setup, get the fish...simple..,