I don't have any experience of the "Solution" saddle, but I DO have experience of the TreeFree saddles, both the Exmoor and the new "Tor" saddle which they've brought out.
I had a lovely little Exmoor TreeFree Saddle, which I'd tried first, and then managed to find one on e-bay. Loved it! Used it on a 12.2 Exmoor pony and my 15.1 trad (wide) cob. You can get different sized gullets for this saddle, which is useful if swapping around with horses. My 15.1 trad is short-backed and this saddle suited him fine. I sold it - to finance the "Tor" saddle which is the TreeFree version of a GP saddle (wish I'd kept the Exmoor now, such a nice versatile little saddle). The Tor is fantastic, it has a nice narrow twist with it and it is the ONLY saddle that I can ride a wide cob in, and still feel comfy after say 2hrs in the saddle!
I use the TreeFree Tor saddle on my youngster, who is a wide short backed low-withered coblet of 13.2'ish, who I know would be impossible to fit in a standard/treed saddle. It suits her fine and I haven't had any issues with it. She has the Wide gullet in.
I have ridden - or rather tried to, on both my cobs - in a Barefoot Cherokee, and it just put me way too wide, just didn't work, in fact it was painful for my hips, which is why I've changed to TreeFree.
I have to say that I have received absolutely First Class service from the TreeFree people, Johan and Andrea. They came out and fitted my youngster as I was worried about getting a good fit for her, and that reassured me a great deal. Luckily I'm in Devon and they are about 40 mins drive for me. But IME their customer service is excellent.
You can get the Exmoor saddle (the later ones anyway) with stirrup bars in the "Forward" position which will help those riders, like me, with dicky hips, to be more comfortable, so if buying one second-hand this is something to ask about. You can also get them with a forward girth-groove. But they rarely, if ever, come up second hand, neither do the Tor saddles. Which says it all really. When they DO come up, people often ignore them as they don't realise just how good these saddles are! OR you get the opposite problem, with people like me who DO know and who will snap them up, particularly the 16" size.........
The stirrup bar is a conventional one, so you don't need to worry about "closed" stirrup bars (something I particularly dislike about the Barefoot).
I can't praise TreeFree enough; theirs is the ONLY saddle I've found which I can actually ride in for any length of time without being in pain and/or discomfort. I have had two independent experts i.e. equine physio's and soft-tissue massage, who have both said that my old cob's back is in excellent condition from wearing this saddle!
Oh, just to say, if going for a TreeFree, bear in mind that for some reason their saddles do come up big; so if you buy an 18" it will be HUGE, it really will! The 17" will fit most horses & riders, but may be a bit small for anything under say 14.2, particularly if short-backed. You'd really need a 16" for a pony.
Do also bear in mind that you can trial these saddles for a week: cost me (from memory) about fifty quid when I tried it, you really need to try before you buy with ANY treeless saddle TBH as they're all so different.
(PS: edited - please note that I have not jumped in any of these saddles. Just don't "do" jumping, period. Not a good idea with dodgy knees unfortunately
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