no. it works, but falco is too good at piercing for me to be able to live without lightshield. that said I can't really powershield 70% these days cause I don't play vs falco enough..and i'm mostly training vs fox atm. I still get the occasional powershield though..and leffen's dashback is still pretty much guaranteed. If you have a regular falco practice partner i recommend learning the powershield...but then the falco will stop lasering so much and you will start forgetting how to time it.
dash back is guaranteed powershield though...counterpick FD, take half the space on the stage, and if he dares to laser you powershield wavedash out and put him under pressure...with no platforms he doesn't have any decent escapes except roll away, so you will get back any stage you gave up.
This all assumes you can CG on FD though, while we all know marths can't chaingrab cause they never play FD cause people always ban it (as they should)