Only drawback to any tube unit is that tubes are not as durable as a solid-state circuit and, if you want to nit-pick, a well designed solid-state circuit will always produce less noise than tubes. Just try a few and pick one you like the sound of. Take specs away and use your ears!
Personally, I like to take a DI from my Warwick Hellborg preamp. I also have a Radial Bassbone which also sounds fantastic (and works for Will Lee too, apparently).