Thoughts on the medic crossbow: It's not for combat at all, as you're nearly useless even compared to the syringe guns.
However, the ability to have one shot of burst-healing is useful, as is healing across an unsafe gap beyond the reach of your beam. It'd be much better if you could overheal with it, but I'll take what I can get. Note that I say "one shot" because unless your timeframe is very long (5 seconds or more) then firing once and immediately switching back to the medigun is ideal efficiency. Over time, the crossbow heals faster than the medigun, but it doesn't build uber, making it not useful over long periods of time.
The extra regen from the combo of both weapons looks really nice, as does the taunt effect on the new saw (which may be slightly OP on clustered A/D maps).