Cstick on attack gives you access to pp dtilt, which is amazing as a spacing option and to make it difficult for certain characters/players to approach, and you open up pp utilt as a kill option to better space its weird hitboxes. With ftilt, you can already pivot it, so pp ftilt isn't much of an addition.
I still use smashes with my cstick instead because I feel like they benefit me more as a player. I feel like one of Roy's most needed things from seeing sets and my own gameplay is closing out stocks better, and I feel smashes are best for that as a cstick option because I do things like use usmash for tech chasing and spacing fsmash in certain occasions. I like how easy it is to utilize frame 6 dsmash with the cstick, even if I'm not the biggest fan of how weak the initial swing often is. I still get what I need out of pp jab, pp shield, and just moving back a bit to do whatever.
I play default controls, so I never need to set tags
I've always been off-and-on about investing in pp tilts and that control scheme, and I'm still questioning heavily if I want to invest in bidou or not.
After the 9th and 10th is when I'll sit down with control schemes and what I still need to learn fundamentally and Roy-wise, then probably make a decision. The biggest barrier for me learning bidou is how fickle the cstick already is online, I wouldn't mind investing otherwise. Most likely I'll stick with default controls as always, but learning bidou despite potential frustration with it randomly not working online is still really, really tempting....