I use a remote A.C. power switch for my Roku's. Works great and I get a fresh boot
each time I use my Roku.
A fresh boot before each use isn't gaining you any increase in performance. You're not hurting anything either.
You're waiting for the device to boot up before you can use it, but other than that it's a wash. I wouldn't buy a switch to turn a device like this off and on.
Yes, I have to wait for the Roku to boot.
BUT, I have also had dozens of problems with my Roku 2 XS over the last
year that a reboot solves. Mostly the screwy remote issue where button
presses are duplicated or worse.
I also use the remote A.C. switch to allow me to disable a network device.
Helpful when I am using "tcpdump" to check for problems on my LAN. I
can avoid seeing the Roku "ping" my router.