I was a Coast dealer back in 2009-2011. I personally liked the non lounge Radiance a lot. I think their filtration system worked really well, they used quality components, had good power and therapy, plus the elevated 24" waterfall looked really nice. I would make sure to get it with full foam insulation. Also, and this is just my opinion, I would avoid the 7HP pumps. They use 3" plumbing and to my knowledge you cannot get replacement pumps anywhere else and they are expensive if they ever fail. I'm not a huge fan of proprietary stuff.
As for the company, they were ok, nothing good or real bad. I have had very few issues with the spas I sold which is good because their tech support in my opinion is average at best. Main reason we stopped carrying them was international shipping was expensive, parts orders did not ship the quickest (I'm in Wisconsin, FYI), and outside of the Radiance, Zenith, and Freedom, I was not a fan of the other layouts and we wanted a complete line from a single company.
I cannot comment on the dealer, but they are going to be as important as the brand you choose. Make sure you are comfortable with them and that they have after sale support because eventually all spas need it. If the dealer checks out and the price is right, I would have no issue owning a Radiance.