Aux for me - only ever used it once less than 50yds from the pontoon when the main engine cut out and wouldn't restart, but it probably stopped my boat either being on a rocky beach or into a jagged rusty steel shipwreck - with 20kt of wind you would not have paddled into it even if you were He-Man. Mine does about 4kt on 6hp at half throttle, and about 4.5kt on full throttle (just adds noise), so I usually set the throttle to half, lock it in place and steer with the main engine as a rudder, works well and while I wouldn't want to be in very rough conditions driving like that (steering response is a bit lethargic) I'd rather be sitting at the helm than perched on the tube. The only thing I haven't sorted out is an external fuel feed - I am not sure how far I'd get on the litre or so of fuel in the aux tank, I do carry cans but you wouldn't want to be refuelling a hot engine at sea!
Thankfully the old Humbers have a sensible "un-trendy" flat transom so mine is just bolted on the transom, no brackets to snap and fall off.
I don't even carry paddles as there isn't much passing traffic to wave at, hence the fact I carry an aux