@PP: Shield stopping allows you to retreat much more than if you just run->hold back. Since you use A you probably don't notice though... =/ Still, try to do : dash->retreating nair, and then do dash->shield[1frame]->retreating nair. The difference is a bit smaller with fair but very noticeable
also: Marths should start aiming for each thing they do out to hit, or rather to have a purpose. Not getting punished if you miss should be a bonus, not the aim of using that specific move. Sure, sometime intentionally whiffing is a good bait, but it should not be the center of your game like many marths use it today.
This also aplies to dash dancing. Why do marths rely on it so much? You're intentionally limiting yourself to just "confuse" your opponent most times. In this metagame, top players know how dash dancing works way to well that "confusion" to work.
While it is true that always moving is good (which is the "true" purpose of dash dancing) when you do it so predictably it loses it purpose.
I'm not saying don't dash dance, dash dancing is a great way to broaden your options once you've started your dash. Oh, and I hate the term Dash dancing btw. It has come to imply that the forward and backwards part of the "dance" are even remotely alike.
The important part is to not do that first "dash" (which limits your options greatly) without purpose.
First we have dashing forward. When you dash forward, it indicates that you want to gain space/approach. Since having stage control is so immensely good in this game, moving forward is a necessity.
However, you need to consider why that you should choose to dash forward, instead of walk/wd/jump forward. Yeah, each of these options have their own faults, but none of them is as limiting as dashing forward.
Dashing forward real (non metagame influenced) use to me is that it moves forward quickly. While it is slower than WDing, it doesn't have any start up lag (this lag is much more important than some realize I think, it heavily limits characters like luigi and ice climbers)
The fact that dashing still gives you quite a few options is indeed nice, but since it still limits you quite a bit you should be very aware of what exactly dashing forward limits and how you should cover these limits.
A important aspect to dealing with these limitations is realizing that its not just "what can I do during my dash". It is how these limitations affect your decision to dash forward in the first place, and how you should condition your opponent while not dashing so that these limits do not cripple you.
I could go on for a lot longer but its getting really late ;o
oh and a quote from armada about playing my marth with falco:
"I can at most shoot about 7 lasers a match - and 6 of those are when you're in the air"
powershielding = broken