SMC receiver pack is big. I bought it but never installed.
I run 4.5 with rollout 8-10mm higher than 4 cell. I don't have run time issue with Novak smart boost but yes it's little bit soft.
Little black pack next to SMC pack is 200mAh receiver pack I used before I changed to Booster. Takes about 80-120mAh per 8min run.
My Novak booster fits under servo with bit of rewiring.