Well, this is certainly something I'm curious to play around with, but I guess can throw some thoughts here in general about PDL... from my viewpoint, which is of course going to be about challenge fight applications. (And as such, any issues I might have with the things are not necessarily things that matter, with balance not being considered for hard more and extreme and all that)
Patience is really nice, since the one time I actually took the time to use DL on a lengthy battle, it sure was extremely lengthy. Due to DL having such good defenses, it wasn't exactly hard either. In these cases, PDL (even when it was 1%) would greatly cut down on the length of a fight like that. Of course, there is one specific issue with this: It doesn't really make DL any better at dealing with these fights. It makes it faster, but not stronger. It'd be different if we were talking about a battle where DL would be in danger of losing though. In that case, speeding the fight up could reduce the risk of losing, but the other side of the coin is that you're giving up a trinket, that could potentially make that risk a zero again.
At the end of the day, the issue with Patience is that it's actual uses from the viewpoint of someone VERY patient are actually very few. DL shines with it's defenses, so it doesn't need to do things fast. If the defenses aren't enough, you don't want more attack, you want more defense.
One potential use for Patience is that the extra damage could outplay healing bosses, but with various challenge stuff going on, the healing numbers are completely insane, and turning a "100" to a "200" isn't going to cut there. From recent memory, there's like, ONE boss that didn't have scaling healing, and Patience would be helpful there.
Now, I know I just said that challenge shenanigans are not included in balance, and that still holds true, but you know what would make Patience a lot more worthwhile? Give it something to directly combat healing. I know that kind of goes against the idea of "patience", since after all, healing means you need more patience during casual play, but at the same time, it actually means the patience will pay off even against ridiculous healers. In theory, if PDL could increase the opponent's healing resistance while increasing it's own damage output, that would still work off of the patience angle.
[Note: This is absolutely dumb, and should probably not be a thing, but I really want it, so... :P]
I can't really say much about RDL, since I'd have to give it a more proper look first. I like the idea that it allows people not too into defensive gameplay use DL though.