I have. They ride/sit totally differently.
I am short, with German Ponies - have 2 Link II's. They are shorter saddles, deep seat, sit you fairly upright.
I took at Link I to try - much longer, not as deep, put me in a chair seat
I have a Connexion for sale - which is almost identicle to a LinkII. Same cut back shoulder, shorter tree, deepish seat (not quite as deep as LinkII). A bit narrower twist but rides the same feel to me.
I actually just picked up a Link on trial this week so this is a timely thread!! While I have to first admit to being an eventer and therefore having a limited knowledge of dressage saddles, i have found this saddle to definitely be not as deep as the link II. I am long legged and have a shorter backed horse, and it seems to work well for both of us. I had originally been looking for a wave but found this one at about a third of the price of the wave and figured it was worth a shot. I had my dressage coach sit in it, and while she agreed that the seat was not as deep, she was happy in where it put my leg (and hers). I contacted Schleese and they basically said the same thing, good for short backed horses, not as deep seat. Hope you find something that works for you!