I really don't want a buy back clause, I'd honestly be willing to pay an extra 5m if it meant they couldn't sign him back.
It's better than not getting him at all yes but the way I see it is we get to borrow the player and we pay a bond, we look after the player, work hard on him then once he's good he leaves and we get or bond back and a couple extra mill back as a thank you. But if we don't develop him into a good player we're left with him and we don't get the bond back.
You'd be better off just to loan him rather than sign him with a buy-back clause. If we loaned him presumably we wouldn't have to pay a fee and would most likely just have to cover his wages which wouldnt be that bad. In the unlikely situation he doesn't perform at all and has behaviour issues he goes back to Barca and we've lost nothing.
If we were to sign him with the clause Barca would only have to pay a couple of million to get him back, which we'd just about lose on paying his signing fee, joining a new club and signing a new contact he'd also ask for more money so we'd be paying much higher wages too. We'd be risking our cash but for no real reward because as soon as he comes good he goes and essentially we'd make nothing.