I use a guru - works great, super lazy. Really like it for starting the burn, does not take the extra time to stabalize that the basic UDS does. I have managed a 1am start up in under 5 minutes. Hell, one time I did it in probably 2 (but that was not intended)
A single blower on the side will cause a very uneven burn in your coals. It will probably cook fine - but looks terrible... Likewise, a single vent on top will cause uneven temps (at least if you are cooking on the hot side). When I cook hot, I either rotate my food, or the lid. I like having the elivated smoke stack as my lid holds water. If you use a Weber lid, ymmv.
If you search my posts - I ultimately rebuilt mine and put a false bottom in the drum with a bottom blower. It diffuses the blow 360 around the edge of the drum. Like the Guru, it is overkill - but works quite well.