From my experience MIO devices are one of the best branded devices for hosting iGO navigation. Program runs stable even on the old models with 64mb RAM (M300/400, S series...), GPS is locked very fast etc..I unlocked many different models and I was always surprised how smooth can Primo run on these devices. You should unlock your Mio and install Primo on it and I'm sure you'll be satisfied. You can find many tutorials how to modify it. If you'll need any assistant, feel free to ask, but first of all check the unlock variabilities which you can find here in Mio section.