Posting for future reference, I reached out to Tango Down about their slide stop on a gen 4 10mm. They say it fits but it is not tested for log term use. They recommend replacement at 3K rounds. FWIW it is not obvious to me why the slide stop is a wear item but what do I know?
Text of their email below:
“The VTSS-001 does fit the G20; however, that said, we have NOT tested it with a high round count. Since the 10mm models are not very common, we haven't modified everything to include those model listings in product descriptions/packaging. GLOCK does recommend on the 10mm models to change the factory slide stop every 3,000 rounds due to extreme slide velocity and weight, ours would require similar replacement.”