auto's rock! mines auto and ive done quite a few mods and im quite happy with it. Its great for being on constant boost when changing gears. I find i cant launch mine as good as a manual but my rear tyres are ****ed too so that could be the case.
I wouldnt convert it, when buying second hand manual boxes you dont know if the sychro's are ****ed or its got any leaking bearings. I found this out the hard way in my old car. The car seems to lose its integrity too.
I wanted a manual too but i settled on the auto as i got mine for a great price, and im still happy with it.