I never castrate and have had no complaints - either about meat I've sold, nor about boars raised by others for meat.
The boar taint thing is a complex issue, and I'm sure there are threads elsewhere about it. I've researched this quite a lot, and there are numerous factors involved, including breeds, rearing systems, and feeding, so if anyone wants more info, message me.
I've never had it in traditional pigs and I've sometimes kept boars to seven or eight months before slaughtering. I only ever had it in Landrace/Pietrain crosses which went to slaughter later than planned. My husband didn't notice any taint, but I could smell it whilst cooking, though the taste was fine.
You may be interested to hear that pressure groups are lobbying for an EU ban on castration by 2018, and it looks as if the EU will have a ban on pig castration done without anesthetic by 2012.
I don't separate males from females at weaning - never have done, and have never had problems. The "riding" that someone spoke about is an expression of dominance, not sexual behaviour - same happens with dogs, even when castrated.