The Oppo BDP-83 is a good choice, and oddly, I noticed the other day when it was playing that the disc popped up as HDCD on my display (Tool 10000 Days!). The Oppo is solid, but still doesn't have the build quality of the top Denons, and it doesn't cost nearly as much either. I also have a 2900 that served me very well for SACD and DVD-A. There are stand alone SACD players, but I can't think of a single DVD-A player that is not a universal player since you typically need the video aspect for most DVD-As. I have a stand alone CD/SACD player and it is a bit more difficult to setup the multichannel without video capabilities.
I haven't heard the A1, so I can't comment on it, and I have also only heard the 5900, not the 5910, and I was impressed with that one already.
Last time I checked, Arcam only supported DVD-A, not SACD.
Note too that these two formats are highly likely to die off in the near future, so I wouldn't invest top dollar into high end gear for either of them.