In my cab I have the Xbox, Marquee light, TV & speakers being powered by the smart strip.
In my case, I couldn't set the bios to boot after power failure (same goes for some PC bios out there as well), and if the Xbox didn't have constant power, I'd have to deal with time & date settings every time I turned it on without the mod. That wouldn't really be taht big of a deal, but if there is a solution to not have the problem, then why not do it.
[EDIT]
Would you be running windows?
If you are running windows, then unless you are just turn it off while windows is running, then your plan wouldn't work. If you shut windows down properly, then it wouldn't boot back up as you plan.