I've used them for about seven years. Current favourite is the 'Dipper', a thick asymmetric triangle. The corners all have a different radius, but the same bevel. Each corner has a different 'feel', and it's possible to produce a range of toned by turning the pick round. I also have two different thicknesses of their mandolin picks. They are expensive, but they last a very long time without any visible wear; the fact that they are expensive means I tend not to lose 'em! I've had the current fave for about three years.
One interesting thing; because of the pre-cut bevels, you have to order right or left-handed picks. They only work one way round.
Tim