Thought I would pass some information along on Bullfrog Spas, since there is not much out there.
We have had our 552 for about 1 month now and couldn't be happier. The jets are very powerful and the varied jetpacks offer excellent massages. The foot jets are awesome! Although my wife is 5'7" and I am 6'2", we both fit comfortably in all the seats.
We are located in a smaller community, so our only other choices were Emerald and Catalina. We wet tested all three and decided on the Bullfrog. We didn't like the Emerald because the jets were not very strong and the layouts didn't work for the height difference. The Catalina was very good. We actually ordered one, but the dealership let us wait to wet test the Bullfrog, because they didn't have any in yet (new Bullfrog dealership).
Although the Catlina and Bullfrog were very comparable in jets and comfort, we really liked the plumbing system and the jet pack idea in the Bullfrog. After sitting in all the seats, I cannot imagine changing them, but who knows what will come out in the future.
At this point, I would highly recommend wet testing a Bullfrog before purchasing a hot tub.
Will try and keep this site updated with longer-term performance.