I've got an Abetta we use for our pony mustang, who is ridden at most 1-2 times/month. The gals who ride with it like it. It is a bit small for me, but I may try riding Cowboy with it sometime. For the price
($365), I'd say it is an excellent saddle. The fenders and stirrups strike me as kind of cheaply made, but they could be replaced easily enough. It is light, and seems comfortable. The male in me appreciates it's relatively level seat, versus the kind that rise up sharply in front. The construction of the saddle seems very good overall.
I've never bought from the saddle shop I'm linking to below, but it is a good, brief review of flex saddles.
"If you have a bad fit to begin with, the flexible bars may make the fit tolerable, but by no means comfortable for the horse. If you have a good fit to begin with, the flexibility will allow the horse to work with the saddle, giving him more freedom of movement in the shoulders."