I am considering Heine Straight 8 Race cuts for the G20.
Any endorsements?

3 of my Glocks currently have Heinie straight eights, I like them a lot. I would give nod to the Heinie as far as a slightly more precision / target sight due to the slightly narrower front blade. Also, their night sights use 2 tritium vials/ dots (1 front, 1 rear) and there are no large white rings around the tritium vials so in daylight the sights resemble a target blade. In low light, the alignment of the 2 dots is vertical which some like as well. You can always purchase standard / non-tritium Heinies for much less $

I have the Slant Pro on my G21C. They are very similar to the Straight 8 except for no night provision. I shoot mine as is in IPSC/USPSA  and idpa competition. Race cuts would be better, and even better still is a race cut rear and a Dawson fiber optic front.