The main difference between the TA05MS and the TRF416WE is the location of the motor. The TA05MS has it more midship (just behind centre) and the 416 has it situated in the rear.
A rear mounted motor will have more weight biased towards the rear, which can be good for racing modified touring as this will give the car more rear traction than a mid-mounted motor. That being said, if you're running stock or super stock you might want a car that transitions left/right easier which a mid motor would do.
Dont worry about the TA05MS drivetrain. I have been having issues with mine running a 3.5T and lipos that calculated out to 89560rpm, which is way too much for the MS drivetrain.
5.5T motors have around 6000kV which means you're be looking at the 45000rpm range and thats much more manageable.
-Mark