Hmm I'd forgotten about RJ11, I like the small flexible cables and positive click (just like RJ45) and IIRC there are 100s of cheap premade cable lenghts in any phone shop.
The socket however is hardly any smaller than RJ45, even a 4/4 is 18x14mm.
Another thing is the 24 gauge wire (some even 26), I need to run power and I wouldn't get much down that with a long run.
Rob