Thanks to you both, really helpful replies and just the sort of information I was after. The S-Tac is certainly in the running and would I'm sure be fine and hopefully better glass than my MTC. However the model you linked to above at OW is the SIII I was looking at and is a great deal and actually cheaper than the illuminated S-Tac, hence my interest in it.
TBH I am after a scope for long range on my Finnfire so the SIII probably would fit the bill. Can anyone maybe tell me how the S-Tac compares to the SIII glass wise and also is either going to be the big improvement over the MTC Mamba I'm looking for? I have always been happy with the MTC's for rimfire and air rifles and as said love the multiple aim points of the SCB ret. But recently I seem to noticing some whiteout when looking anywhere close to the direction of the sun, although it may just be my wafty old eyes!