Have you ever driven a vtec car with vtec disabled? I have, a couple actually, including mine. And trust me. You lose power compared to what you will have.
If you have a way to adjust the fuel maps, then I guess you could just use a switch, I'd say an RPM switch over a toggle though, because with an RPM switch you won't have to go and hit the switch every time you want to go vtec. Or, you could get an VAFC-II which will let you adjust fuel and vtec.
Apexi VAFC II - AutoCarParts.com