Comparable price aside, I'd be much more comfortable with a proper live map from R-Tech than the unknown quantity of a tuning box or lesser known generic map, considering how weak the 140 turbo seems to be.
A mate of mine bought a mapped 140. Turbo died. Replaced with a hybrid and made a safe 210bhp with a map from Ben at Shark (another good mapper).
Worth considering a bit of turbo work if just for reliability.
Do you know if the 170's have a stronger turbo? Mate's looking at getting his mapped with just a plug in job, but it claims 250bhp. Seems a big jump without having to uprate anything else, or do the diesels just respond better?
I don't have much experience of the 170, but I can tell you that 250bhp from a tuning box is nonsense. Advise him to steer clear!
I think the 170 will map over 200bhp, but nowhere near 250bhp. Again, a live remap would be safer, and achieve the best results in terms of power and drivability.