I tried SCO out for the first time last night with the one fitted to my base Python MkII (bought with ARX earned in-game).
It's clearly a straight upgrade for the 1,500ls trip I did to a nearby planet, it wasn't a long enough trip to cook the ship or have any downside other than fuel usage & I can see myself adding it to most if not all of my fleet, particularly to remain competitive against other Cmdrs. There will be some practice required to interdict other Cmdrs but it should provide significant advantage to those that are paying attention & want to quickly move to another location to capitalise on an opportunity or avoid becoming a victim.
There is clearly some skill to using it (arguably not enough although perhaps there is more to it I haven't seen yet) making in-system trips both less dull and more interactive, and reduces the time exposed to danger in supercruise so the concept is a good solution to a lot of gripes about supercruise mostly being a boring time-sink. I found it very handy for escaping gravity wells in particular.
I do wonder whether human NPCs will gain this feature making them harder to interdict but overall it seems like a good way for Cmdrs to fast-track the boring travel times while retaining most of the dangers of supercruise during the deceleration phase.
I do like the SCO mechanism (now that I don't have open up SpecialK's overlay to cap frame rate to 24-30 while using it) and once one has it, there is the real choice of when and where to use it, or not.
However, there is now essentially no downside to equipping the drives, so it's depreciated conventional FSDs for most uses, leaving no increase in choice with regards to planning or outfitting. We're all going to be using them, when we get around to upgrading new sets of FSD modules.