Don't forget about Flux very happy with them on my kids boards. When I rode them they were great!!!
Yeah, In my opinion the 2 best brands for bindings are Flux and Union. Both are made and warrantied to last a lifetime, are completely adjustable, and are made to work well with almost any boots on the market. However, both have 1 different benefit and 1 different downside:
The benefit of Flux bindings is that they are tool-free, with the disadvantage being no baseplate dampening.
The benefit of Union bindings is baseplate dampening, with the disadvantage being that you need a tool to adjust any part of them except the ankle strap and highback.
I've had a pair of Union bindings for an entire season now, and unlike my previous bindings, NONE of the screws on them came loose at any point. When you rotate the ankle strap and ladder, their screws don't rotate, they stay in place.
If you're interested in these 2 brands, whichever one you should go with depends on what you'd rather have: Tool-free adjustment or shock-absorption.
With Forum soon to be melting away, it wouldn't be a bad idea to consider another brand in case you ever have a warranty claim. Burton also makes REALLY GOOD bindings, but for the same price they're not really as flexible as Flux and Union, and you can only really get good dampening if you get a pair of the EST bindings....but for that, you'd need an EST board (Channel).
If you're happy with the Forum bindings though, go ahead and stick with them in the larger size! You wouldn't have to worry about any warranties if you got a refund and ordered a larger pair from dogfunk.com, because they have a lifetime return policy. If you're not satisfied, you can return them at any time
Just don't tell the dude at the store if you do that, unless he has a similar policy!