We have S/O at 50%.
It got us on the market and I genuinely feel like a home owner, the 'shared' aspect isn't an issue at all. Yes we had to ask for permission to change big things like the kitchen, but when we come to sell or buy more, the valuation of our half has to take into consideration the money we've spent/value we've added and be offset as such, so we don't share that added value with the H/A. Our mortgage and rent combined is £400 cheaper than our private rent.
I've no worries at all about reselling, it was the 12th shared ownership one we'd gone in for, it was so hard to get one. We only got ours when the previous buyers failed to get their mortgage at the last hurdle.
Compromises we had to make were moving further out than we'd planned, and almost all we looked at were on or on the outskirts of council estates which means a mix of people. And knowing we'd have to do work to it (cosmetic but a lot) but then we will be here several years and if anything big/structural arises that's not our problem, it's the H/A. With Brexit and the uncertainty of the market we felt like it was a lesser risk right now too.
Top tips: get your MIP, proof of finances etc and IDs verified first, this saves you time.
Out of the five different housing associations the 12 houses we tried for, only one worked in a way were all applicant put in their forms by a deadline and they were all assessed then chosen- the rest came down to first come, first get their paperwork in. H/A will only process one application at a time and once that's in, unless there's an issue which is rare, you've already lost it.
This said, the home owners do have some sway- we managed to woo most of the owners and they all informed the H/A that if the applicant failed they wanted us next in line. This is how we got our house. They promised us to be next if anything fell through, and as I say right at the last minute one did, and we got it. but that was 4months between viewing and getting the phone call to ask if we still wanted to go for it.
Some of the H/A will send their "affordability" forms, then you send them back and someone looks over them then calls you to stress test. Unless you pass this you can't view the house. Which wastes more time. Save the forms, have them filled and ready to ping back the minute you get that email to say a house is up for sale. Else you have to refill every single time and it's a bloody ball ache.
Sign yourself up to the website and get notifications for the houses in the regions you'd like. You really have to be on it.
Oh and they'll only use approved financial advisers for their stress tests etc too. Save time by finding out which ones near you are, then go ahead and get started with them so that you can look at the 'normal' market at the same time but if you do spot a S/O, you're already half way through the formalities as you're ok'd by the right guy before anyone else.
That's all I can think of, best of luck!