I think that bringing back the Halo 1 AR would be a good idea, make it a dedicated short range weapon, instead of something that can't decide if it wants to be short range or mid ranges and gets itself in a tangle trying to do both.
However I'm goin to hold judgment on the pistol for now until the release of ODST. The H1 pistol was great and it'll be nice to have an alternative to the BR, but the auto-mag looks like it might be even better. Let's just wait and see eh?