Light shield edgeguard doesn't work in Marth ditto, as Marth likes to take his time dropping to the ledge after having his shield hit by the upb. *note: works if the opponent can't sweetspot, but vs a half-decent sweetspot, the person up-bing will grab the edge first. It might work if you fastfall after having your shield hit...*
Husband definitely knows more than me. Just because I beat him doesn't mean my opinion should be weighed more. 0-6 I DI away and down as it's generally inescapeable if the other Marth's timing is decent. Away and down let's me DI away a decent distance, as well as touch the ground somewhat fast, so that if they are off by a few frames in the chase, I have time to spot dodge or roll when they go for the regrab. 7+ I DI fully away, unless I see them using the uthrow, in which case I use slight left or right DI, so that my arc isn't low enough to get hit by the utilt, which is generally what people will go for after an uthrow at that percent. Slight DI or no DI from an uthrow at that percent lets you jump out a lot easier.
About the teching question: it doesn't really matter on the recovery, as long as you hit the button at the proper time. If it helps you, go for it. It won't make you airdodge unless you press the button.
Husband definitely knows more than me. Just because I beat him doesn't mean my opinion should be weighed more. 0-6 I DI away and down as it's generally inescapeable if the other Marth's timing is decent. Away and down let's me DI away a decent distance, as well as touch the ground somewhat fast, so that if they are off by a few frames in the chase, I have time to spot dodge or roll when they go for the regrab. 7+ I DI fully away, unless I see them using the uthrow, in which case I use slight left or right DI, so that my arc isn't low enough to get hit by the utilt, which is generally what people will go for after an uthrow at that percent. Slight DI or no DI from an uthrow at that percent lets you jump out a lot easier.
About the teching question: it doesn't really matter on the recovery, as long as you hit the button at the proper time. If it helps you, go for it. It won't make you airdodge unless you press the button.