I really haven't had any mana problems even with the limited ramp. I've had some of the creature based ramp before but removed it for more zombies. The deck runs pretty fast as it is. I think it's just a case of wanting to fix something that isn't broken out of an attempt to make the deck "perfect".
ETA- I've decided I probably should add some more ramp, two pieces of creature based ramp and
Farseek but I went into the problem I'm having with doing that atm in another thread.