I know what you are saying, however ROAR is very slow to update their manuals. In fact, in the "official" rulebook, they still specify "05" Size brushless motors, which are essentially 540, 2-pole motors. All 550 motors are longer than the maximum length for an "05" motor.
(See rule 8.10.13.2 for the rule relating to 4x4 SC racing, and rule 8.8.4 defining what an "05" motor is.)
With that being said, if you look at their "Approved motor list and check for the "4x4SC" class, most 550 motors and the 540 4-pole Pro4 motors are all on the list.
http://www.roarracing.com/approvals/...lessmotors.php
If you're at a ROAR Rules race, or a ROAR sanctioned event, then I could see it going one of two ways:
1) If they follow the rulebook to the letter, then everyone will be running 540 2-pole motors.
2) If anyone is allowed to run a 550, then they have to allow the 4-pole Tekin motors for the same reason. (You might have a hard time pressing them to allow other 4-pole motors as none are on the approved list for that class. You MIGHT be able to get away with the castle 1410 as it is approved in the "Modified" class. It's the entry for "060-0021-00 3600KV")