Arcane Shot and Rotation for MM

Hey guys.
Just changed from SV to MM through guild requirements for raiding but have a question about Arcane Shot and shot rotation.
The guilds main Hunters havent spec’d for Arcane Shot in thier MM talents and tell me they dont even use the shot as they do better dps without it and have less mana drain.
The thing I see with mana is you can always go from Dragonhawk back to Viper, load the mana back up and then change back to Dragonhawk but you lose dps during this transition.
So whats the general concensus, is Arcane Shot something I should spec for or not?
I know as SV Explosive Shot was my friend.
Now shot rotation, this is what was on our guild forum from our main Hunter:
I have been having a few mana issues with introducing arcane shot in my spam rotation. At moment i have current spam of:
Rapid fire
SSti
CS macroed with SS
Aim
Arc
Readiness
Steady
and the shot rotation is fairly easy after initial cooldowns:
1x CS
1x As
1x Arc
2x SS
RInse and repeat and hit other cooldown u have whenever they are up sacrificing SS
However after getting on latest hunter spreadsheet it seems that a small improvement in dps can be made by getting rid of Arc (changin the arc talents) and simplifying the roation. It also saves a lot of mana and should never have a problem with full raid buffs.
1x CS
1x Aim Shot
3x SS
Glyphs: Kill shot, glyph of the hawk, serpent sting.
The extra points u hit into rapid fire means that is up probably once more during boss fights and the spare point into +hit helps gear. ALso you can drop trueshot aura if u only interested in using this spec for raiding.
Had a go at reviewing MM vs SV spec and MM still comes out on top for overall damage, burst damage and damage vs moving fights.
So again is this a good roation to work with without using Arcane Shot?
I always like to ask for a second opinion as the more advice you can get will never hurt.
Thanks.