Ruhk wrote:
Speeder Maul needs Flight, or MotF 2.
Flight would help overcome his large-base-ness, which tends to slow him down, and get him stuck. Flight would allow him to zip in and get decent movement, allowing him to pull of a good Charging Assault every now and again.
MotF 2 would allow him to do a Rage+Assault, and then most likely Cleave. Or be able to Rage + Charging Assault and then re-roll if you miss.
CotS's Quad attack is a great draw, then chance to pull off 120 damage is sometimes irresistible, but his low-ish attack makes him miss more often then not. Also he actually has some defensive abilities, unlike Speeder Maul. Furthermore he is slightly cheaper, helps if you're building a squad around him.
In terms of true competitive play neither are really viable options, though some make a case for CotS in 100 points, but the GFC has shown me that both can be very deadly.
I know it's over the top to make this comparison, but with the newer high defense force users CotS seems as effective as Komari Vosa. Waste a turn to get adjacent and then swing and miss 4 times. Yaaaa hoooo.
Like you said for Speeder Maul; base size and lack of deflect are a big deal. I don't use deflect with him unless it's a crit though. 3 force points sucks big time.