TG - Section 15 of Primo 2007 states
15. No person may, unless authorised by the Secretary of State, remove or deface an ear
tag or tattoo applied under this Order.
So you can not legally remove the breeders tag, but only add you own, which is personally what I would do.
We have most breeds at OaklandsPigs, and generalisations about the characters of different breeds are far less important to how you bring up your pigs (nurture over nature). Any breed will be friendly if teated right and hence most smallholders like the breed they like and I would choose on shape and colour and spend time taming.
Taste wise pigs are what they eat, and therefore any differences in taste for outdoor pigs will tend to depend more on time of year you buy and kill, or what the season was like etc. etc. rather than breed. Some breeds are larger, some tend to run more to fat, and different shapes and sizes affect the joint sizes etc. and will also affect taste to a degree.
On temperament - and with tongue slightly in cheek - in general terms, we find that OSB's are a "more forward" breed (tend to come to you and follow you around), GOS are lazy and don't move unless there is a good reason and are grumpy is disturbed, Saddlebacks are laid back in life and quite happy to go with the flow, Middlewhites are stubborn and pushy madams, large white freak out if disturbed or see something strange and run around like headless chickens, Large Black are really friendly, Tamworths are either really nice or really lively (not in between) so trouble or treat. Suspect that has set a few hares running, but we love them all !!