I had the valve guide issue on mine at 20.000 km.
No warranty, too bad.
I'm not far from needing replacement for the second time.
Begin to feel increased play. Have a little over 40000 km on it now.
When browsing through all the messages and opinions about it, it appears that the 1100's do not have the issue. At least not at the same rate or frequency.
What would be the difference in design with respect to valve stem, guides that seem to have cured the problem.
I know older models had larger diameter stem.
Did they go back to increased diameter stem or what?
I have been on the assumption that when they fix the initial, failing production series valve guides (at least on warranty) they had different part numbers to replace the original ones. Thus this fix should be more durable than the original ones were. In your case 20k kms seems to be the same. This is a bit puzzling but behind this link it is in my opinion rather clear they should have used different part numbers etc
Mine were changed also twice, but the problem was that they did not get the fitting of the guides right, the new valve guides were disjoint from head and started pretty bad oil burn. That happened to me just a 1-2000 km after change, so I guess it is not the case for you because you have been running already 20k. In the end they changed new heads for me, it was on warranty because my bike was 04 manufactured but sold 06 thus it was still on warranty.
Started 1972 Honda CB350, bought new, still runs
Then Ducati M600 -99 from -01 till -07,
Now MTS1000 -04 since -07
