No doubt, that Rainbows are every bit as good as the Bostons in performance. I'd be a liar if I said they weren't. However, the Bostons are no slouch, and they are American made. I prefer that when I can. All that aside. If I had a pair of Rainbows in my possesion, I would not hesitate to use them. Thay are good stuff.
I just prefer to run the Bostons as they are as good as 95% of anything out there, and road noise will usualy cancell out the last 5% of the better detail of the $7,000 top-of-the-line Rainbows. Germs, are good. Profis are better, and the Reference line is for guys with more money than they know what to do with.