I commute on both types. The front shocks make a very nice difference going over bumps, taking the edge off. On my commute there are more bumps than I care about and I wish all my bikes would go as smoothly over said bumps. As for the weight - if you lug food, emergency repair stuff and clothes around, on a rack etc then that does not count toward all that much. You're not going to set uphill speed records, are you? So don't worry too much about weight.

Seatpost shock? I can't say I feel any diffs there.