What I don’t like about that letter is that it does not guarantee the kids who accept this Spring admission by May 5th WILL BE the first to be offered Fall admission, if they offer it all. It kinda seems like it from the letter, but what if kids accept this Spring and then a wave of Fall admissions off WL are given to people who didn’t check off the box. I hope they wouldn’t do that, but if I was offered this, I would talk to admissions before accepting. Find out if this puts you in the front line for Fall or it only guarantees you Spring and nothing more.
And honestly, I would still hold a deposit on another school if Fall admission is the only thing you really want.