Can't say I've ever heard someone have issues with the wakes of any of the LXI/TXI boats. Every one of them I've ever driven from 04 - 14 drives great, tracks great and skis great!
I've got a couple buddies with LX boats, and have taken sets behind a few Echelon's. The echelons definitely have a harder edge to the wake and are tight on space.
If you're wanting to go up 5/6 years there are several 04, 05, 06 RLXI's out there. I recently bought my 04 last summer. It needed a bit of work but after I got my hands on it, put a new steering cable, new tilt column and greased the rudder assembly it drives and tracks like a new one. The open bow in the RLXI provides plenty of space for a few people to lounge around and catch sun! And the rear trunk pads also are a great place to lounge. Plenty of storage too.
I think you'd have to go to an 06 RLXI in order to do any ZO conversions.