Does anyone know if there's a size comparison gallery of the BoA vs BoJ versions of G12?

well heres a pic of the american version compared to the original Dino Megazord
http://i676.photobucket.com/albums/v...dMegazord5.jpg

and heres g12 compared to the supertrain
http://oi38.tinypic.com/15n0x7p.jpg

if you dont own Supertrain hes freakin massive and is slightly taller than an Armada Unicron, I think ive seen pics before that G12 is also as large as a Fort Max

Only one I've got. The two biggest ones. The other two are the microzord and the Minipla model kit.

http://i209.photobucket.com/albums/b...ntai/Go-on.jpg

As you guys have so awesomely pointed out, the original BOJ releases dwarf the BOA imitators :D

It's not a imitator it's BOJ USA cousins that's still as good

I think it's pretty clear that it's a poor man's knock off. The Engine Soul functionality is almost entirely removed, the molds have been simplified and made of cheaper plastic, the paint apps are sparse, the colors are wrong, and it's overall about 20% smaller than the real deal. BOA may be the "cousin" to BOJ but their DX mecha products have been substandard since Operation Overdrive.

why are the american rpm zords smaller than the japanese go-onger engines

Not quite Jungle fury mecha is the same mood as BOJ one with just light up fist removed and BOA ant half bad there still good if you can't afford the Japanese one

RPM didn't have as much of a focus on the Engine Cells. In fact, the show probably could have cut them out entirely and there wouldn't be any real change in story. The Souls were Go-Onger's gimmick and even if BoA could still import the Japanese toys, most of the functionality of the Engine Souls would be nixed since the RPM Zords aren't characters like the Engines. All you'd probably get are a cycle of generic rev noises.
The only color differences I can see is that the Kishamammoth is burgundy while the Mammoth Paleozord is standard red. A (rather unlikely) Reprolabels set could remedy some sticker and paint app problems alongside some Gundam markers.
And while smaller, the RPM Ultrazord is easier to display. The Gigzord might be smaller than the Samurai HaOh, but the Samurai HaOh's giant motor could NEVER fit on the top of the bookshelf where I keep my Gigazord, Unicron, K'Nex Alive Fighting Phoenix and Beanie Baby "Ireland Bear Trio."

As for plastic quality, I'll just take your word for it since I don't own either The RPM Zords or the DX Engines. Yet.

Not really 'as good'. As someone said before, comparing the BOJ and BOA versions are like night and day. Just way too different. The BOJ release is better. Thats all there is to it (and its more expensive)

I agree with this. The only thing I'd say may be 'better' on the BOA version is the connection between the whale and Engineoh is more secure.

I know where you're coming from on the sizing front. I have the full Samurai Haoh and have no idea where to put it so its in storage now.

But the quality being better is true. BOJ Engine G12 everything clicks together fine and feels 'solid' (aside from Jumbwhale's connection, and its not loose, just hving two small clips holding such a big back pack would never have been enough). On the BOA one there were way too much stuff that felt off. The additional arm upgrades all hand down loosely. Those heel things on G9 and G12 like to detach and so does the face guard on Buson (sorry I dont know the US names). Neither of the masks actually cover up Engineoh's face to a satisfactory level (unlike the BOJ one). Theres probably more but I'll leave it at that.