engine not revving past 6k but only when in gear

[Dead Eye]

I had the same problem once while on a track day. But mine was due to a small era on my part.
While on track i got a fault on the rev counter to indicate EXUP problem.  So i stripped, cleaned and re fitted, then went back on track. Only to find that it would only rev to about 6k (i think). I returned back to the pits and found that i had put the cables on the wrong way round. ( Schoolboy era.).
Have you/anyone done any work recently.   

Ps. When it was out of gear and on the stand it would rev freely.

This applies only to the Gen1 1000, not the 600

Testing the bike with the clutch in or in neutral is probably a good start. When you say it won't rev past 6k rpm - do you just lose power or do does the bike begin to stutter / cough / stall? If it just loses power than I would assume there is some problem with the fuel / air. Is it possible that the bike has been restricted (to 33hp etc)? I would have thought the mechanic would have picked up on that, but you never know...