Throwing in my $0.02...
I used cat5e on my first C/P and i will for sure 100% NOT use it on my next one.
By function, they are called twisted pairs because inside is 4 pairs of wires, twisted up. These wires will stay that way too! It's going to look a LOT uglier underneath with twisted pair than with wire straight off a roll, or with untwisted wire (Franco's).
The disconnects (if you decide to go function-over-cost) wont crimp to cat5e properly. The wire is just a bit slimmer than you'll be able to crimp easily. You can try remedying this by doubling the wire over on itself, but you'll find it still will be loose. I managed to get mine crimped but even the slightest bump when you're building/tweaking/etc. will pull out wires.
Basically, Cat5e is great if you have several lengths of it handy that you can sacrifice (I'm in IT, i had TONS of cat5e available to me). But in the end, you're going to have less headaches, and things will be more solid if you use a thicker gauge wire (see: wire that matches your crimps).
On the other hand, if you're soldering your wires directly to your buttons (please don't! save yourself the re-work trouble now!), things might be easier for you.
Points of interest:

-versus-

Also, that's DB25 extension cable coming off my terminal strips. Inside was wire that was even thinner than cat5e, don't think you'll like crimping that either...