You have to decide if it makes financial or convenience sense for you. Before we fulltimed, I figured I could do a lot of laundry for $1,200.
We then went fulltime and made it 14 months before my wife demanded a washer/dryer. The only thing that fit was a vented combo.
When we traded rigs 2 years later, we decided to stick with the combo and got one for the new rig.
VENTED or bust. The UN-vented ones is what most people complain about. Knuckle up the courage and drill the hole. The first hole is always the hardest.
I like our combo and I even like the small load size. Quick to grab some things and throw in, and quick to fold when it comes out.
More info and installation pictures/notes here:
http://learntorv.com/clothing-washer-dryer/
Hope that helps.