I carried a 5D/24-105 combo plus G11 last year in a Lowe Pro slingbag. There were places and times when I felt comfortable taking out the 5D and others when I wasn't. As in other countries, there are places you can go comfortably and places you shouldn't go without a guide. Tourists are approached constantly by vendors, beggars and others; even the police expect payment if their photos are taken. The tour I was with was accompanied by a plain-clothed, heavily-armed Tourist Police officer who helped immensely.
Anyway, at the Sphinx I was jostled and knocked down some steps, breaking the 24-105. The G11 served well thereafter, except on the Nile. Many really neat scenes that needed just a little more reach, a little more IQ. The new Panasonic GF-2 with the 14-140 might be the better choice if I do it again.
Bill McClure