Okay, the alarm went off, the neighbors called, and my diary reminded me what I had to do.
I'm glad you took my "advice". Great job on a pretty clean (HT)PC build, considering the lack of space in the Solo (I would know as I own one too). Pictures are fine. I was worried about the clearance for a Mugen 2 in this case, so glad to see that it is indeed useable. The way you have your cabling is similar to the way I had mine. (Before I disassembled my build of course, which is another story for another time.)
I don't think you need to change out the IDE ribbon cable for a round one, unless you have one spare to see which one you prefer. The ribbon ones have the advantage of being folded and taped down, however, they do look somewhat awkward nowadays. I have both types. But I have a SATA DVD-R drive now, so no more need for the ribbon cables there. Only for an IDE HDD and FDD, which I still insist on using.
Did you softmount your harddrive? doesnt really look like it is, I'd recommend you do that to take care of the last vibration noise from it.
I think he meant "suspend" as it is already "soft-mounted" using the silicone grommets on the HDD tray as it appears. Try the suspension if you haven't already. It will give you an idea of the difference in acoustics. If you are happy with the grommet mounting provided, that's good as well, and more secure, especially if you move your case around a lot, which I also tend to do.
Well done on a clean and to the point build. Don't underestimate your abilities!