There are canisters for ponds! So yes there is surely canitsers for a 180 without any fussy pipework. I have a 90gal and I can't wait to go much bigger. The possibilities of aquascaping, choice of fish etc are so much better.
perhaps people are not looking into what the OP is talking about..
There is a big difference between upgrading to a larger tank for say a regular scape. Stones/wood with some monster fish.. Or upgrading to a huge tank with plants that require much more work, supplies and even bigger rise in energy bill.
If cfsin has that type of money to spend then go with the biggest tank you can fit in that space.. Other than that 75-100g is more than enough to work with in regards to a planted tank.
That's exactly why I started this thread - my committal is really not a part of the equation. I love the hobby and can't wait to get started on the new tank. I first wanted the pro and con feedback from those of you who have these tanks now! Please, keep the feedback coming!