Geoff,
The Mankati guys are an Ultimaker ripoff, they have issues with delivery and service. I heard bad things about them. Pity, because the printer looks impressive (though haven't seen it IRL).
Personally I'd rather get the original Ultimaker with dual heads. They're are a reliable Dutch company, keep the printer opensource, and they're the guys behind Cura. So the money gets spent in a good way, supporting the community and an awesome printer

Ultimakers have different head construction than Flashforges, and they are blazingly fast, easily over 200mm/s, and layer height printing below 0.07mm. There was a thread for such HQ prints on the Ultimaker's Google Groups. Much more expensive though.

Now, Flashforge.
When you add head fans to the dual-head Creator this machine is a killer. I own a flashforge, and have a lot of experience with repraps, and some with proprietary printers, top range stuff. I printed shittons of stuff on the Flashforge, with shittons of materials. It's not perfect (oscillation interfering with print quality, loud) but I wouldn't change it for any other in the price range.
ATM I fried the head power section apparently and looking for solution, but Flashforge is a real workhorse and I love that printer.

Price/quality ratio is out of the roof imvho.