Ah ok thanx, but in theory it should be sufficient?
Yes it should be fine (based on my 100% lack of experience with that unit
Should i go straightup for the Mega?
Your call entirely. If you want to go for the mega and when the project's done you find you could have based it on a Uno there's nothing to stop you swapping a cheaper Uno into place, loading the sketches and strapping it into your enclosure; and conversely if you start with a Uno and run out of pins you can either upgrade to a mega, or there's ways of adding inputs, outputs, PWM pins etc with additional ICs and circuitry.
You'll find the Arduino ecosystem is nothing if not flexible.
All the best with your project, Geoff