I imagine you have a Q-loc (clamp feed neck) already since the stock ones are useless. If not get one otherwise you could find you hopper going walkies if you do any diving.
I have an epiphany which is similar to the Ion, just with higher rated internals. I got myself a freak barrel (insert) kit and an s-rail mount to get a nice gun position. Remember you can get different freak barrel backs so that you can use the your freak barells on non smart part markers should you ever upgrade to a mid/pro level marker.
Having tried an Ego 08, Ego 07 (a few people have mentioned these in this post) and Etek, I personally would go for a Etek or now the Etek2 as the performance difference is minimal, they share similar components and the price difference is huge. Overall Planet Eclispe markers are very well built and seem the most popular amongst the pros.