Not sure what you mean about a 5er working better than a motor home. The big difference I see is the motor home will have a lot more living area than the 5er. Much of the interior in the 5er would be dedicated to the toys. Another benefit would be traveling in the motor home when not wanting to use the toys. Much more comfortable in my humble opinion. The few toy haulers I have seen, travel trailers, not 5ers, have pretty spartan interiors. I'm sure there would be a little more in a 5er but not a lot. I expect the living area would be very cramped but the bedroom probably would be sufficient.
I believe he meant to write "quads", aka ATVs (I think "quad" refers to their 4 wheel drive capability). Toy haulers are often used to carry an ATV/quad or two. Doing the same with a motorhome usually means pulling a large trailer, perhaps large enough for a car and the ATV/quad. And there are now some Class C motorhome toy haulers on the market - I think Coachman has one. Here's an example: http://home.earthlink.net/~dortolf/?x=24&y=8