I run a spool in my XRAY (Electric) and the drivetrain wear has increased considerably. Also tyre wear increases as the outer tyre is not able to travel at a different speed to the inner tyre to compensate for the wider arc it travels around corners. I'll try it on my MTX-3 soon. Your still able to achieve good turn in with a spool with a couple set-up adjustments.
p.s. i believe the Kyosho/Sirio boys (Bertin, Spashett, Shimo, etc) were running front spools in their RRR's at the last 200mm IFMAR worlds in Brazil which they happened to dominate!