Having been a Vandersteen guy for 30 years, I can say that it is all a matter of taste. The Model 2Ce Signature is a warmer sounding speaker than the 2Ce II Sig. The 2Ce Sig. II is somewhat cleaner sounding and a touch leaner overall. One word of caution about the 2Ce Sig II, they're 2 versions. One has the standard polycone midrange and the newer (latest model) has the woven midrange from the 5A. It is a better sounding speaker with this newer driver. The new midrange was introduced back when the price increased to $2395 a pair (sometime mid 2012.) You can take a flashlight and shine through the cloth. The polycone is a plastic kind of look where the woven is identified by the actual weeve look on the driver. It's a duller look. One thing about Vandersteen's are they all seem to manage the "Vandersteen" house sound in one form or another. Vandersteen seems to never stop "Tweaking" his speakers. Each successive model (or change) gets a little more out of the design. The newest Model 2 is simply an unbelievable bargain at full retail let alone bought used.
As for the Ayre amp, it sounds soooo much better used balanced if possible. It does mate well with the speakers but they're are other options available also.