After I get to test this bad boy out (waiting on rings), and it performs as expected, my question will be, “keep or sell the FS102?” Maybe trade down to a 3” apo which I don’t have. My lineup now includes a 3” Vixen Achro, 5” JSO and an 8” sct. Would I benefit from downsizing the 4” or keep the FS102?
I sold a really great 105mm F6.25 LZOS triplet to fund my TSA 120. Because there was no portability penalty in moving to the TSA 120, I would do the same today.
Unless you have a 100mm-class apo that is considerably lighter than a TSA 120, there is no real reason (other than maybe nostalgia) to keep the smaller scope.
Moving to an 85 or 90mm gives you the portability advantage over the TSA 120 and a viable reason to consider a scope in that aperture range.
I think 90, 120 and 150mm-plus is a nice aperture spread for refractors, as is 100, 130 and 160mm-plus.