I have no experience of the FLS Sprint.
I have flown the Firefly and yes it had a slow roll rate, other than that it was (and is) a fine little aircraft well suited to EFTS (where I instructed on it.) The Tutor has had problems with it's prop, principly because of the poor engineering of the initially (poorly) selected model, the current prop is fine. CFS have insisted on some odd procedures for the Tutor which doesn't help, but the airframe is fine. The avionics of both types are over complicated for the AEF ( where I operate it.)
I wonder how many here who proffer opinions have direct operating knowledge of and instruction time on these types, rather than grumbling hearsay from the corner of the bar?