Ahh so AI isnt too expensive, cheaper than a pedigree proven boar (thinking £250-£500), though pedigree registered weaner boars would be nearer the £100 mark.
The boars I've worked with so far, have all been friendly, but I have seen the marks on other people to know not all are like that, I also know a Large white x boar who if he leaned on you, your quite likely to get crushed. I also go on to holdings where sometimes the boars haven't been tamed as much as needed and you do need to be careful, they have just been treated the same as the sows, and in some cases this isn't enough handling. Or in some cases they have been allowed to push or shove when younger and now have no respect, and a boar with not enough matings can be a grumpy boar, at least i have found this with the larger breeds, unlike my mother's KK boar.