Its a calculated risk with castration as all surgery , you'd need to ask your vet how many small animals they castrate ( they will do more rabbits than pigs)
Having the smell of sows can turn then barmy .
Our GP7 (sow) used to chase GP8 (sow and her long term cagemate) round and try to jump her .
GP6 (our boar) was neutered when we got him (we had GP3 neutered , there is a minimum weight and age , surgery is fairly straightforward but you need to keep them on towels , look out for post-op bleeding or abscess and they take 6 weeks to go sterile)
It doesn't change how they think.
Our boar was very "Oh Hello " Leslie Phillips voice but sows will get them to Jog On if they don't want to welcome them.Doesn't stop him trying , he's all purring and doing the little waggy bum dance 
When we bonded GP6 and GP7 (our last two) it was hair raising for DD and I because we'd tried over and over to bond our group but they wouldn't .
They accepted each other but he is very much under the thumb, she can kick like a mule and pee back.
When your sows are in Season do you get signs? Mine were snipey with each other and their pee stunk, luckily it lasted 1-2 days then they were lovely again.
Castration was £58 for our boar about 4 years ago.