I agree with the time vs money thing. I probably would steer towards Xantech if it was for someone else's system, too. Assuming this works fine, it will be much simpler to setup for me.
I never agree with the logic that "you spent that much money, so what 's another $300?".
Yes, it says it is momentary. It can toggle, too.
If you want to spend a few more bucks, here is a different one -
[Link: rentron.com] It is a bit more configurable.
As far as opening the box . . . If you have the same one as me, the UP and DOWN buttons simply pop out and you have easy access to the connecting wires. Should be a simple solder job.
I'll let you know how it works.