AR 9 DT was called AR 11 and AR 10 was called AR 12 forever, but since the time some table came up and it actually showed that technically AR 10 DT is AR 11 (response time between ARs gets 150ms lower per level, AR 10 is 450ms iirc, AR 10 DT is 300ms, so it's 11). Apparently the current trend is AR 10 DT = AR 11, and then you got 10.33 and 10.87. I just call them AR 9 DT or AR 10 DT to avoid confusion.
Anyways, to be honest:
AR 10.3 is "ok". There are a few maps with this AR that can be FC'd by not extremely good players, not many tho, most of AR 9 DTeable maps I can think of (ignoring AR) are extremely hard per se and I think my fingers are more than enough to count how many players can somehow FC them (talking about people who can properly FC them, I can FC stuff like Yasashisa if I retry
a lot, if I could play the AR of course). But then you got a few maps which can actually be full comboed by not rrtyui tier players, but I don't think it's really worth it. (Try Bamboo Dance on the AR that fits you most, if you can't easily FC that then give up, I'd dare to say that map would have top 50 DT FCs if it wasn't AR 9, with this I mean easy FC, no more than 3 or 4 plays)
ARs over that are... meh, what are you gonna do? Search for [Hard]s with AR 7 to DT HR? Good if you want to farm pp, but that's it.
AR 11 is just... I think it's pointless, mostly because you will have to play [Insane]s with DT HR (unless again you want to farm pp on [Hard]s) and even if you can read the AR, OD is gonna be just too high, and the effort it requires to properly play max AR is not worth it. I can't think of any player that can play it to be honest, there was some guy from Sweden who could but got banned (for some reason I don't know about) and then if I had to guess I would say some speed player, but then again not worth the effort.
tl;dr: Don't bother playing those ARs, very few maps to play them on unless you are a high end player already, which I'm quite sure you are not.
Tip: Playing very high ARs, for many players that are supposedly super good at them, means also to retry a few times to remember hard to read parts. Right now I can't play AR 10 at all, yet I can play a few AR 10.3 DTs just because I remember the map a little bit, so I don't need to react to sudden triplets or streams, or weird jumps/patterns, because I already know they are coming. Not being able to play AR 10 properly I almost got an FC on
http://osu.ppy.sh/s/27915, not a hard map but I couldn't see a thing but inb4 retried the map some times.