It's all about feeling comfortable in the saddle. Everyone is built differently, so you can't say 'yes buy it it's great' or 'no don't buy it it's horrible' because each and every one of us is built differently. A saddle that I love, someone may hate, and a saddle that I hate, someone may love. Typical scenario with the Isabell.
It all depends on how you are built. Personally I would hate to be locked into place every ride. You will not learn how to hold an independant seat, and when you need to move around on a green horse to exaggerate certain aids, it makes it might hard when you are 'stuck' in the saddle.
So definately have a ride or two in both saddles on YOUR horse (I like some saddles one one horse, but hate the same saddle on the next horse! - it depends on how the horse moves and is built).