I actually cancelled my Shouki order today because I have no affection for that team/combiner and they're just too damn small to fit in any of my collection sets.
You know, I think this set is the perfect example of the dilemma of MP scale figures. At least when it comes to combiners.
I personally do not own any MP scale 3rd party combiners, but I've done a lot of research into them because I wanted one (but now I don't). In order to make a combiner at this size and poseable, you would need insane ratchet joints due to the volume of plastic packed into each limb. Or you can make your combiners into bricks like the G1 toys. I own the G1 Predaking. However, while the heavy-duty ratchets might work well when combined, they're no fun to mess with when not in combined mode. Though not all of them require you to engage with those joints uncombined. Just watch any review of someone trying to show off the poseability of any of these 3rd party combiners and you'll feel the discomfort through the screen. If they wanted to make a combiner lighter, they'll have to use lighter plastic, and I'm not sure they would be all that durable.
So I get why Takara made their set smaller because all the 3rd party MP scale combiners have been a pain in the ass to pose or even combine. Smaller bot, lighter figure. But in making them small, they can't scale with the rest of the MP line.
I feel like if you want to collect combiners, have them scale, and be fun to mess with and pose, you have to go CHUG or Legends scale. Hell, even CHUG might be pushing it a little. The Legends scale seems to be a good size for combiners when it comes to weight. Of course, shitty design can still ruin them, but they're well designed, they better than MP scale. Hell, I think the Takara train bots might as well be Legends scale at this point. I think they're small enough.