The improvements in ready to run N Gauge stock has been phenomenal in recent years. First Farish moved their production to China following the buyout by Bachmann and then Dapol came onto the scene. The overall bar continues to rise. Those modelling post-grouping era will more than likely find some RTR stock to satisfy their requirements and on the whole the work required on it tends to be minimal.
Of course, wheels must be changed to conform to 2FS standards. Mick has covered the reprofiling of the Farish and Dapol wheels, but as I mentioned before, I had lost the wheels from some of my Farish coaches. They have been running on 6mm disc wheels with 15mm axles, though today I received from Shop 2 a nice parcel. The 7mm disc wheels on 15.2mm axles are designed to fit the new Farish bogies and I must say they run rather well. Additionally, for me, they are visually far superior to the original wheels (even though they are a giant leap over what was available a few years ago). You decide for yourselves:
Apologies for the clunking great N couplings still in evidence! They will go. And soon!