I should probably put on some Nomex long underwear before posting this. I've got the Vixen variant of this Synta-made scope (ED100sf, later style with the dual-speed focuser). A few months ago, I was out at a club star party, and happened to set up near a fellow who was fortunate enough to get one of the newer, limited run 100mm f/9 Tak fluorite doublets (FC-100DL). Later in the evening, under excellent seeing, we both ended up spending quite a bit of time on Saturn, and shared views. We used the same eyepiece (his wonderful Clave, 6mm IIRC) in both scopes, and the view was as good as I've ever seen in a 4" scope.
But was view in the Tak better? Maybe just a smidge in terms of contrast, but the observable detail each scope served up was identical to my eye; cloud banding, Crepe ring, brightness variations in the A&B rings, etc. Saturn isn't a critical test for false color, but I couldn't see any in either scope, and I the only false color I've ever seen in mine is lateral color in some of my eyepieces. The Tak owner commented that he wasn't super happy with the single speed R&P focuser. To confirm this, I found I could snap to focus a bit quicker using the fine focus knob on my lowly, oft-tweaked Synta dual-speed Crayford. (But I'm still seriously considering a focuser upgrade for heavier loads/imaging.)
Sure, if money were no object, I'd take the Tak (with a Feathertouch) over mine. But in the long view, mine hangs in there with the best for a very reasonable price, allowing me to put my limited astronomy budget elsewhere (...and now I really want some Clave eyepieces ). To sum up, I don't think you can find better bang for the buck than the Synta ED refractors.
That said, before you take the plunge, think long and hard about the Skywatcher 120mm f/7.5 ED--same focal length/image scale, and only marginally heavier. It should be a noticeable step up in deep-sky reach and planetary detail, assuming good optics at thermal equilibrium in good seeing. Cons are longer cool-down time and, at least in theory, slightly greater chromatic aberration. If I didn't have a larger scope (13" reflector), I'd definitely want the extra aperture in the refractor.
I hope this info helps.