The Shadow is a small amp designed for IEM's, and to me is very neutral. It really keeps the soundstage open, with no frequency range more emphasized than another IMO. Full bass, smooth mids, and a nice smooth but crisp treble. Imaging on it is great. Every thing seems to be placed where it should be. Coming previously from a Fiio E11 to that, it was a huge upgrade in terms of SQ. I'm a fan of a very balanced, neutral sound, and for me it fits the bill perfectly for portable use. It uses a rechargeable battery that is built in, and the battery life is phenomenal. I would guess I get around 80hrs from one charge. I have yet for the battery to go dead on me, I've only charged it a handful of times in the few months that I've had it.
The Hornet is a bit bigger, and is powered by a single 9v battery. I have a rechargeable in there, and the power adapter charges the battery when installed. It has 3 gain settings, and can drive some of the more difficult cans from what I've been told. The HD700's aren't very hard to drive, but definitely benefit from a good amp. The sound is a bit warmer than the Shadow, and to me, the soundstage is slightly narrower, but by a very small margin, and is still very good IMO. Still a very smooth midrange, a full bass, but the high's are more on the warm-ish side, but not muddied at all. It pairs wonderfully with my HD700's, which are infamous for their slightly bright treble due to some spikes in the 5K and 10K areas.
I'm not great at describing the sounds I guess as I type this, I just go by what my ears like
Admittedly, I haven't heard a large range of different amps, so I don't have much to compare them to. I originally bought the Shadow based off of others descriptions of the sound, and by Ray's track record of customer service and the small size of the amp for portable use. It impressed me quite a bit, and when I wanted an amp to use with my HD700's around the house, I actually picked the Hornet up from another member on the forums here and was just as happy with the Hornet as I originally was with the Shadow. I would love to try some of RSA's desktop amps with my HD700's, but they are a bit more than I'm willing to pay at this moment, as I'm working on upgrading my home theater audio setup now with new speakers and separate preamp/processor and amp.
Hopefully I answered your question, and if you have more, I will try to answer the best I can.