Thanks for that, as I stated both bullets seem to shoot quite well and I was wondering if I should put all my effort into experimenting with one or the other.
I only shoot black powder and most of our competitions in our black powder club are usually at 100 meters, sometimes at 200.
The main difference I can see between the two bullets, apart from the 20gr weight difference is that t he lighter bullet is .050" shorter and has more grease grooves. I have experienced no leading issues with either.
So, in nutshell, if you had to choose between the two, bearing in mind the  way it will be used, which one would you choose ?.

Your target will tell you which is the better choice/load. Tested the BACo 400gr against the Saeco 640 370gr bullet a while back. The BACo was right at 1moa at 200yd and the Saeco was 2moa. The 400gr BACo will generally shoot 100-5X, or better, at 200yd when I do my part.

Am loading the 400gr with 56gr of 2F at 200yd & 59gr of 2F at 300yd. The 420gr mold casts at 413gr for me with 20-1 and I shoot it with 61gr of 2F at 385m. I used to shoot the 413gr bullet at rams/600yd, but rang a ram a couple of years ago so now shoot a 439gr Money bullet with 65gr of 2F at the longer distances.