Diamond and I believe it is Comet both have an SMA multiband antenna. I have used both and they are about equal.
The Diamond is the SRH815 (they also have a dual band, the SRH 519). The 815 is about 6 inches (maybe a bit less) long and is a very slender whip. It may not be quite as good overall as the RS 800, but it has served me well over the past year or so.
If you want to keep the compactness of the 396, then the 519 is really a good choice. If you look closely at the
396 in the photo, I have the 519 attached. You cannot see the entire antenna, but you can at least get the general idea.
The 396 with the 519 antenna is only an inch or so larger than the PRO 96 without an antenna.