I believe the correct answer is:
Neither one is correct.
Both kits are somewhere between 1/48 and 1/55. Somebody on RT.com did the math for us and we figured that 1/55 would be a bit smaller than the MPC and 1/48 would be a bit larger than the Imai.
Personally, I love the MPC sculpt. I own the models to make all three of the Legioss but damn, after seeing this I'd never be happy with my own attempt Don't hold the MPC's fighter mode against it based on the comparison pic, the front "fins" are still pushed down instead of being in their proper position making it look kinda sloppy. Looks like the back flap that fits the shoulder mounted sensor (whatever that thing is) fits a lot better on MPCs and the front fins are anime correct on the MPCs (as far as their folding behind the mech in battloid). For a model, those Legioss are super impressive though.
I never understood where they got that center missle stand and top mounted gun though... those don't appear in the series do they???
Does this Jung character still build and paint models for people? Maybe he can do my Legioss too!
Interesting. Thanks for putting me in the know on the scale. It still looks like the model and the MPC are exactly the same size height wise though. I still have three of those IMAI models waiting to be built.