besides weighing and being about the size of a box of cigarettes, i love the "phase" switch enabled second out jack, which lets you avoid the dreaded "where the hell did my rig go?" when your onstage with a dense band.
Aside from being the most transparent buffer on the market and having a ton of headroom to preserve dynamics even with extremely hot pickups it's also the 'swiss army knife' of guitar pedals. I can be a direct box with balanced or unbalanced output, clean boost from unity gain to 20dB, A/B switch, or a phase corrector allowing you to use both channels in parallel in an amp with out of phase channel inputs. Plus it's built to outlast the human race. You get alot for your $125!
The phase switch on the Axess reverses the phase of the iso out jack. If you run two amps (or 2 channels), they can be out of phase. this will put them back in phase. Go to Axess's website and you can download the manual. Great unit and nice and small.
I have never used one (..............I know, I know why post then) but I was chatting to a few guys down one of the local music shops a while back who had good things to say about the Lehle Sunday Driver. New it is over $150 so you would have to go used but may be worth considering.
really any of the small single buffers for around $45-60 will do. i prefer JFET over opamp buffers...to me opamps have a bit of a "piezo"ish sound to them, JFET hype the highs just a bit, but that's better to my ears.
lots and lots of misinformation about buffers out there. my advice is grab a JFET based one, try it out, if you don't like it you're only out $50 (or sell it and you're only out $10). then grab an opamp based one and try it...i'm sure you'll like one or the other.