Has anyone had any difficulty fitting a Nitron road shock?
No, fitted a good few over the years, great shocks. There's 3 types NTR 1 - 3, each number represents damping adjustment, 1, 2 or 3 way, cost goes up with each, all can be fitted with hydraulic preload adjuster at extra cost. All are built to suit you and your riding style when buying new, if you buy second hand, check if possible what they had the shock built to or it could be too soft/hard to suit you. That said it could be rebuilt to your spec. My advice if your planning on keeping the bike buy new, direct from Nitron using their website.
These are the best replacement shocks out there in my opinion, even the base version is 100 times better than OE, R6 or BMW, as good as Ohlins this side of a track, half the cost like for like and it's British