Where do you get the bad reports on Castrol? I've used it for years in everything with excellent results. I do use Mobil Racing 4T in the TBird and it has done a great job, but I see Triumph is now recommending Castrol instead. I can't imagine they would do that without serious testing and a good reason to do so.
Castrol has updated their formula since the most recent white paper oil test that amsoil put out. I read somewhere that Castrol used many bikes to develop their new oil formula (Power RS racing) including a triumph (not sure model). In the white paper castrol power rs r4 was tested (2009 test). At the dealer that I worked at I had a customer that wanted Castrol but could not get it for him due to the castrol formula switch over. I will note that when we disassebled his GSXR 1000 his clutch was is great shape with castrol oil as his choice oil.