The A10 engines pinged badly from new. I should say the high compression engines.
Couldn't agree more.
Alloy head SRs or any other HC motors friends have brought round over the years have always seemed to need retarding a bit, despite owners' occasional reluctance to depart from some magic number they've got in their head, read in a book or were told by some bloke 'who knows'.
To BoN's point about manual + ATD . . . can be done, has been done. Just set timing with ATD wedged open and camring at full advance, then you obviously have the best of both worlds in terms of adjustability to cope with heavy loads or 'big throttle low revs' situation.
But a few things to bear in mind: first, running with a manual cam retarded from its advance setting weakens the spark; and secondly, the chances of wear gradually interfering with the firing interval on manual cams is greater than on fixed ones. Not to mention AR cable arrangements that sometimes jam or self-detach at the cam and / or are impeded by fuel lines, carb fitments etc on some bikes. Also requires a cranked HT pick-up at 45° on the cable side usually on As, and the quality of the available part is a bit so-so.
I have a mix of manual AR & ATDs myself (but no bike with both)and I prefer fixed cams, once having got the firing interval to 180:180° across the rev range.