my only regrets thus far have been the 3AAA lights... I haven't found a CPF worthy one yet. The Husky 3-watt doesn;t really count since I modded it for an 18650.
I'm assuming you just mean handhelds, the Princeton Tec EOS is definately CPF worthy.
I definately regret the Solitaire, I got it at a time when I lost everything and lose it I did and not to mention it's performance. The Princeton Tec AMP is my other, I was hoping for the brightness of my Photon Rex with greater runtime and reading all of these guys talking how the Nichia DS tint is sooo much better than the GS, but instead got a dim, worse tint than my E01, 2 modes barely apart from each other and the need to hold the button for 2 seconds to turn it off. My cat also seems to be able to turn on the AMP and it has no lockout ability.