Used to have the RD Wide Track and it's true, they do put out a lot of water. Part of the reason they work so well, but you do have to be careful about overwetting. Don't pull the machine back *too* slowly while spraying (particularly on berber type carpet), and be sure to follow up with plenty of dry strokes afterwards to lift out as much excess moisture as possible.
Mine was a Quick Dry version, with a knob at the rear allowing you to select either regular/quick dry mode. The latter reduces the solution flow rate, and I found that to be plenty for most jobs. Only for really heavily soiled carpets would I use the regular setting.
A lot of pro carpet cleaners are a bit sniffy about the RD, partly because it's something you can hire from the supermarket, but mostly because it doesn't cost thousands to purchase. Still has no bearing whatsoever on its capabilities though, and for domestic use it's hard to beat. In the hands of someone who knows what they are doing, or at least follows the instructions to the letter, it does an excellent job.