Hi Kathrin, I bought this saddle for my gypsy cob, who took a red wintec gullet minimum, ie pretty wide. When I decided to go down the australian saddle route I did masses of research and this model is the widest you can get without spending hundreds of euros ( or pounds or dollars in fact as you can't get widthed aussie saddles in france). It was great on my cob and width-wise it is also perfect on my little fjord, who is round as can be, it is just a bit too long for her as she is a very short model. I would have thought this would be perfect on a haffy, we also used it on a comtois mare and it was fine although the girth was a bit short. the girth should be ok on a haffy but if not I could help you find another as I am now expert on aussie suppliers - I have just bought a littler stock version from the US for my new mare. As for staying on, personally I will never go back to an english saddle now. After I swapped my gypsy cob for the fjord I used a wintec english, but another crashing fall, this time knocking myself out and breaking a rib (we were in a pony games competition at full gallop which is my excuse) has convinced me that I am too old to fall like this hence going back to the aussie saddle. There is no way i would have fallen off had I been in one that day. I find rising trot fine in one, and canter is basically the same as in a dressage saddle except that you are allowed to push your lower leg forward in these which is more comfortable too. The horn is great for holding on to and also for hanging all your stuff from.
Sorry for the ramble, yes I think this would be great for a haffy. You need a good pad underneath (I used a sheepskin half-lined standard english numnah or a "trail riding" saddle pad. in theory also the serge pads underneath give to the shape of the horse, but I didn't use it enough for that to happen before the new horse. The saddle comes with western stirrups (leather covered) and wide leathers but it can also be used with english leathers. If you buy this I can throw in you my flash dressage leathers (synthetic leather) which is what I used and I also have a brand new set of excellent aussie leathers and stirrups child length as my legs are short!! They are all brown to go with the saddle.
I really have to get rid of this, my new saddle is arriving this week and we are moving and i have NOWHERE to put this!!
Let me know what you think...and thanks for your interest