Agree, unless you moor right up next / under a motorway bridge you really will not notice it - even if it is just a distant "noise" you won't be bothered by it.
I personally think it is a lovely bit of the canal system and have had a couple of great trips in the area.
Personally i never find trains a problem either (unless moored right next to the line) as I find it rather interesting to see them hurtling past while your chugging along slowly.. not sure what it is.. but it just seems very peaceful on the cut even when your in the centre of a city such as Birmingham - so peaceful that you don't noice that you've been untied by the local chavs and that your slowly drifting down the canal...
Seriously though.. you will enjoy the Oxford.
I think the biggest annoyance of the holiday was some private boaters (we were a share boat.. but a very experienced one I should add) who had a bit of an attitude on them.. but we're used to it and it is all part of the fun :-)