Just ordered my yellow ION, can't wait to test it.
As for the OMEN, both of mine have been flawless for over a year. The OMEN is harder to understand and 90% of issues are user error or ignorance. The ION seems like a great value for the money and easy to set up.
Over all the ION will outperform the stock OMEN. But the 1.5 OMEN with new board and cam arms will outperform the ION for a little more $$.
1.5 OMEN has faster ROF, Better reg, better consistancy, better efficiency and fail proof cam design.
ION has less kick, easier set up, cost less and still shoots more than fast enough for most "legal" games. Also ROF modes are nice for rec play. Breakbeam eyes will give little to no trouble so almost as good as cam arms.
As for looks and style, it's personal preference. I like the OMEN but the ION is just plain sexy.
Stock, I'd go ION...1.5 OMEN and I'd go OMEN though neither one would be a game winner over the other.