I messed around with this the other day.
For marth, it seemed like shield grabs were 2x-3x easier to work for me.
It could get you in pretty close before the opponent can react sometimes and get a grab in.
If the opponent tries to attack you, most of the time, due to the forward momentum, you should be able to shield grab it.
People say it's pretty easy to punish, but a marth can just shield grab the attack at will, especially since it comes up so fast.
I also find it a bit easier to retreat after a couple aerials as not to get counterattacked. Pivot walking, getting semi-close to the opponent, and then dashing (C-stick down) to get that extra speed may mix some things up