No, there isn't a problem changing the resolution depending on the television you are watching...
Naturally, the higher the resolution the better the movie will look and the more space it will take up.
You probably don't notice a difference if you are watching on a smaller television, but watch the movie on your computer or HDTV and you sure can tell a difference in the resolutions.
That's why the KVCDX3 template is the best for quality and size to backup your movies to CD's and still look great on an HDTV