Personally, if $30 isn't really an issue, I'd just get the better case. At least from what I've seen/read, people consider the R5 to be better just not enough of a change over the R4.
So, I've started building in my R5, and ugh... I've already run into annoyances, and I haven't even started with the cable routing! There are a few things that I normally find grating when it comes to building PCs. I/O shields with tons of those flanges that push back on the motherboard? Why do we even have those flanges? I always have to fix their positioning to get the board to mount properly. Amusingly enough, it's always the simple/basic metallic I/O shields that never give me any problems (they're too basic to have a ton of flanges), but the fancy ones that you get with higher-end motherboards are always problematic.
Anyway... that's not really an issue with the R5 itself, but it was the first annoyance that I ran into. Now, in what's probably even more annoying than an I/O shield are crappy motherboard stand-offs. The biggest issue that I have with stand-offs are when they have a high tendency to cross-thread with the retaining screw. I ended up with four out of the eight stand-offs being cross-threaded. :\ After swearing a bit while pulling the board back out, I replaced them with some aftermarket stand-offs that I have, and I had no problems after that. I also had to use the aftermarket screws, which are actually just the same size as 3.5" drive retaining screws, because the R5's motherboard screws area different size.
Also, what's with the rear side panel being so difficult to put back on? The front side panel goes on easily, but I have trouble with the rear one every time. I'm thinking that the issue partly has to do with the lack of clips/slides, but the problem that I notice is that while the top of the side panel seems to go into place correctly, the bottom will not. There's nothing in the way, but I normally have to push it down and screw the thumbscrew in.