I have nitron, although i have the top spec one. brought the middle one and got a free upgrade to top spec affter a slight problem.
Love the nitron and highly recomend them.
But if it was a choice between the lowest spec nitron or the run in milage R6 shock mod i would go R6 mod and spend the saving on Ivans or fork springs / Ktec rework if your feeling flush.
Ive done the nitron route various times on many a bike due to the fact there a fraction of the cost of ohlins, nitron's quality is very good and you can ring nitron and ask any advise and tell em what spec and they will build it, on one occasion i had lost some seals from a nitron shock i gave em a call and they sent some FOC, however taking into account the feedback luke (devilsyam) has recieved on his kits id be very tempted to go that route and spend whats left over elsewhere, now regarding your linkage bearings im sure your fully aware as norm the rear lingage has slight play ! so dont be suprised if you change the bearings and than find you still have slight play.
Dave
With regards to suspension I have the mid range Nitron ("Track" - I think) quality kit, good company to deal with, very happy with the performance. Though if Luke had been doing his kits at the time I probably would have gone that route as the performance would probably be similar but the savings would have contributed very nicely towards the cost of getting the bike Ivanised.
With regrads to the bearings, I'd leave well enough alone. Play in the linkage bearings is normal and those that have sought to eliminate it have spent time, effort and money with very little to show in the way of results. When I suggested to my MOT tester that I might change the wheel bearings as a matter of course he looked at me like I was daft and said I'd be wasting my time as there was plenty of life left in them (30,000).
If you're going to replace your shock it would probably be worth taking the swing-arm out and re-packing the bearings with grease as well as re-greasing all the linkage bushes & bearings, but that's about it. I beleive if you tighten the linkage bolts with the bike on the side stand it can help eliminate some of the play.