Not much help currently as I'm in hospital, and will be for weeks still.
But I have both kits at home, partly built, and length wise they are quite the same but Blackstar looks somewhat smaller than Valkyrie regarding the transport capabilities.
Personally I was thinking of using the Valkyrie rear fuselage (the two long ones) for the Blackstar to change it looks a bit. The body (and the wings) of Valkyrie will go for another use, it will form the fuselage for the Arvus lighter with parts from that tiny SM air vehicle which name escapes me currently.