I have a leatherman sidekick with me pretty much constantly for general use at work and home and it’s great. Nice and compact with lovely spring loaded plier action, good selection of basic tools and a really good blade. It’s something I use probably 3 or 4 times every day without thinking about it – just really well designed.
It will be popped into my pack for longer rides, and has been used several times for bodging trailside repairs, repairing kit and preparing lunch but there is no getting away from the fact that you will still need some hex keys and a chain tool to deal with any bike related issues, so it’s an addition rather than an alternative to a normal bike tool.
You could of course get a set of hex drivers but I see two problems with that:
1 – You’ll inevitably end up losing some of the bits
2 – The short shaft on the hex bits and bulk of the tool will be a big compromise when trying to access difficult bolts.
I carry one of these:
http://www.on-one.co.uk/i/q/TOPHMICRO/phaart_micro_multi_tool
And one of these:
http://www.chainreactioncycles.com/Models.aspx?ModelID=7843