Aaah, nice chirpy topic :)
I have had horse & ponies on loan for over ten years, since I was 13 years old. Infact Harley was the first horse I actually paid money for (August 2008.) My family never had the money to buy a horse/pony outright & so at 13 or so I randomly got offered a pony on loan & it went from there.  I worked a Saturday job & babysat to afford his feed & hay & I kept him on a friends farm :) My parents gave me no financial contributions to any of my horses, I organised & saved for everything.
Joey was a 12.2 Strawberry Roan (I have mentioned him before on here somewhere) was a right pain in the backside so much so the week before coming to me he had five riders off in 10 days. He also had me off too on our first ride (bucked me straight off into a full water bath!!)  He stayed with me for two years & I had a great time reschooling him. He turned into a serious king of gymkhana games, hehe.
Rubbish pics, Joey - The King of Gymkhana Ponies!! With a baby Peach on the right! :P
I had 2 more very sucessful loans after that & then I got given, yes, given my beloved ArabXWelsh pony, Inshalla. I helped out a lady, did chores & exercised her horses for her as her health wasnt great. Spent months helping her out & handling her home breed youngster, then myself & another teen backed her together. One day she approached me & said she wanted to give her to me as a thank you:) I finished off the backing process & she was fab. I also broke her to drive. Dream horse!
Then, granted, the situation didnt end with a happy ending which ive delved into slightly before & it resulted in me stopping riding for a good few years etc. My mum hid the photo's of her in a safe place, one of those ridiculously safe places that you cant find when you want to years later ... ) yep, thats still where we are with that one! So cant show you her.
I also have Puddles & Muffet on loan now from their owner. I originally was helping out exercising Puddles & (the now xoclairexo's) Woody & the owner became sick again & couldnt give them the time they deserved so I ended up taking them on loan in June last year.
Ive never had any issues with any of my loans & wouldnt hesitate to loan Harley to someone if the right home came along. But i would be very thorough with my checks etc. I would certainly loan again in the future.
I dont think people should be put off loaning, its unfortunate like with everything in the world that some people do take advantage of loop holes & can not be as sincere as first thought. I think loaning can be (with genuine people) an invaluable situation for both owners, riders & horses if its thought out properly & above board.
Ok ive waffled, its Friday afternoon, my job is hideously boring ... :D Its Friday, im allowed