Omaha is the difficult game. It,s not so easy to win in this. Lots of players just don,t play it at all, because you can loose lots of your own money and usually people, who play omaha are playing it really good.
I don,t see much omaha freerolls (at least with some usefull money) in the lobby. Only the cheap one. Anyway you can practice in that if you want. Right now lots of players can play good even omaha or holdem, doesn,t matter.
I just think it,s better not to play Omaha cash games, even at low limits this can take away your bankroll.
Omaha is an interesting game, but it is very dispersed and there are few games in Omaha, to win something good, you need to play very well and at high limits. So I choose hold'em, sometimes Omaha for fun.
I think that each of these games has its pros and cons .. in Omaha there are more cards, so it is more necessary to make a good hand, but not so easy at times .. there is a very high chance of bluffing. and at the same time several players can have strong hands. .. even there is more risk ... hold'em ..