the regualr silver M also has rubber sealed bearing which is better than the M2 which has a metal shield bearing.
the Silver M was more limited in quantaity than the M2, since the only way you could buy it, is through Tamiya USA directly. (or from HK, or from Japan..)
In my opinion the regular M is more valuable, since it also have all the aluminum turnbuckle, and extra suspension block.
