I was thinking that I didn't mind spending extra money to get a really good toilet...until I looked up the Tecma Silence Plus and see it's over $1000! That's a bit much for me....so, to clarify, I'll spend up to $400.
As I've googled around, it looks like the three I mentioned are good. The Style II gets complaints about sticky ball closure and leaking water valve, which is usually repairable. The Dometic gets complaints about separation between bowl and pedestal, which is never repairable. I don't think I've seen any complaints re: Sealand, but I think the 510 is 1/2" too deep for my space--I need to double check my measurements.