I also started competitive Smash with Melee in 2004, and it feels much more comfortable for the shield to come out immediately upon applying pressure to the R button, even though I fully press it most of the time anyway because of Brawl.
While buffer certainly does make inputs easier, I think the idea of difficult execution making a game more competitively viable is ridiculous. (Nearly?) every 2D fighter ever has buffering (granted, not to the ridiculous extent of Brawl's 10 frames). I mean, you're already leaving L-canceling in, that's enough unnecessary button pressing for me
The fact that it's a new game and is not Melee is a perfectly valid reason to ALLOW buffering, lol...perhaps cap it at 4 or 6 frames or something? Something universal like wavedash timing shouldn't have to be relearned or modified (unless it's really just me having this problem)--character-specific nuances are perfectly acceptable. I suppose you're quite decided though.