Marth IMO has better recovery than Toon Link. Marth actually has a really really good Up-B for recovery in the hands of a smart player and he's MUCH better at the edge which is a big part of getting back on the stage. Not to mention better aerials that only someone like Metaknight or DDD has practical range over in most situations.
You can hit Toon Link before he gets to tether since it doesn't have all that much range, although his tether I guess will save him from stuff if he DIs Metaknight's D-smash downwards. Bomb jumping won't stop him from getting edgehogged unless he's at like 200% or something which he's simply not surviving to unless he's playing against someone like Samus or Sonic. You can HIT through his projectiles if you know what you're doing furthermore.
No, it's not, it has a lot fewer places that it can sweet-spot, and he can't get the distance overall. That, and his only move to increase his horizontal distance is beyond vulnerable. It's got a good hitbox, but that's pretty much it when it comes to advantages.
With Toon Link it's pretty much impossible to get him to a point where he can't recover, so you have to send him into the blast zone, heck it's rare that he'll even need to up-b period because he's got a really long double jump and he's floaty. Marth, that's not the case, once he's expended his double-jump, if you push him far enough out of the way, he's done.
Marth, much better when he's on the edge? (you said "at the edge", I'll assume that it means this because fighting when your opponent is on the ledge and you're not doesn't have anything to do with recovery)
That's a laugh, that's actually one of Marth's greatest weaknesses because his moves are easy to counter on reaction which allows you to send him back to the exact same situation.
Marth's a lot easier to edgehog because the hitbox is very short, T-link on the other hand, has a very long hitbox.
And no, the tether isn't a general use thing, but it's great in specific circumstances, like low angle knockback attacks where he can often completely negate momentum that would take him off, and just as a generalized mix-up.
And since bomb-jumping gives T-link another chance to get at the edge with up-b, again the long hitbox makes him hard to ledge-hog, that makes it better at dealing with ledge-hogging.
And you know what, people can hit through Marth's aerials too, the point is that it forces them into a set of predetermined responses, which makes edgeguarding games a lot easier to deal with.
In general he's got a ton more options and mix-ups then Marth when off-stage, Marth is mediocre at best whereas Toon Link is quite good.
Take this from a Marth main/Toon Link secondary, Toon Link's got a good recovery, Marth's got a mediocre one.