It's a gem with Accu-sim. Either way the 2D Shift-3 through Shift-7 screens are very useful and can add another level of involvement (keep an eye on engine wear, the nifty map screen than can take input from the Flight Planner and allows you to keep flying without pausing and going into the menu to get to MS's Map screen, and then there's Heidi too).
I've flown it with and without Accu-sim, but personally, but either way I found it much easier to fly than MS's J-3, control inputs seemed much smoother and I fly on full realism at all times. It also got me focused on flying it by the numbers which is very satisfying and immersive. And, I feel it easier with than without Accu-sim, strange as that might seem.
The only issue is if you want to dial up a flight plan (and fly realistically) of over say 200 miles and there is no refueling stop then your gonna need the extra range / fuel capacity of the Flight Replica's Super Cub (the extra speed doesn't hurt either). Of course, realism aside, with the A2A you can always bring up the Shift-4 screen and fill'er up in flight, and check the oil while your at it!