Flatstick, havin used (and crashed with...on many bikes) the big R&G plastic bobbins for many years I can say that I've never had any snap or break welds on the swingarm - the plastic has a lower grab (coefficient of friction) than your alloy bobbins so if anything it'll be the alloy bobbins that could cause a broken weld. This is why all crash bobbins are plastic and not alloy or steel - sacrificial sliders... Other issue with your Harris stand is that the rad on the Harris cup is incorrect, a little fettling to the cup solves this - in fact Harris now sell a specific cup to fit the R&G bobbin solving the problem !
Didn't know Harris sold an adapter for the plastic ones. My Harris stand has very sharp forks and fits the alloy type ones great but the plastic ones won't seat all the way down. I'm just not a fan of the plastic ones. The smaller the better IMO. I've had snapped welds with the alloy ones fitted but I prefer them to the plastic as they're much shorter so less chance if touching down in a crash. I think the less chance of it grounding out the better even if the plastic dies slide better. In future I may even remove the bobbins before each ride to prevent this happening. I always leave my bike on a stand though so could be a pain in the arse. A swing arm rrp is £2000 for a blade.
If u use the right bolts then they will go well before the weld even gets stressed - they are engineered to fail on overload - have used aftermarket bobbins or my own make nylon sliders for over 25 years (on TZ, RG, CBR and other race bikes) and have never had a snapped weld on a swingarm - with metal to Tarmac there is greater risk of dig in and more damage, the nylon ones will always slide on Tarmac and not dig in - preference being what it is I'll stick with nylon and save my £2000 from grinding out !
On the blades the hole seems to oval rather than snap the weld. Personally I prefer to fit the shortest possible to lower risk of anything touching down. It's not an ideal location to have a crash protector whether it slides down the road well or not IMO. Them fork/swingarm protectors work quite well but I won't use them I was black flagged at croft a few years back as the rod end snapped off leaving most of the rod and nylon end bung flopping in and out the a l while I was leaning etc I think as it was a race bike and wheels were on and off a million times the rod couldn't take it. Could have easily had me off I it had dug in when leaned over.
