Off the back of this thread I ordered an advancer. arrived today and fitted.
Instantly starting was much better using no choke at all, idle sounds a little less lumpy. Pick-up from the bottom also noticeably better (less fluffy).
Not noticed any great benefit in better pull at low revs, but then I only took a quick blast to the petrol station and back.
Engine does feel a little less peaky and more smooth up the rev range.
One main thing I did notice was less popping from the exhaust on downshift!? Maybe in my head, time will tell.
my only complaint was the machining of that one from ebay was rather tight. I tried to get it on but the locating lug just would not go. I had to get a small file out and take off the edge where there was a small lip. Once lip removed was a very snug fit. torqued up to 60NM and so far so good.
Will update after a longer ride.
thanks, Fuzz