I haven't been impressed with any of the saws on a multitool (the Gerber one looks OK). If you think you need a saw, how about 1/2 a hacksaw blade with some duct tape as a handle? Would be very light, and enough to sort out the bolts.
The other thing you could do is replace all the allen bolts with hex-head bolts, less likely to damage them with a proper spanner (IF they are greased, and IF it is the proper size, not an adjustable spanner) than will and Allen key. Or just go for 5mm allen socket rather than eg. the 3mm on my bike.
Occasionally I use a pliers multitool, usually it is pretty frustrating. Lightweight jeweller's type pliers aren't tough enough.
I've sometimes thought that a locking variety (Leatherman Crunch?) might be useful. Depends a bit on your bike - good derailleur hanger and V-brakes rather than cantilevers or Mavic centrepulls make things easier.