Such a great mecha. I mean what's not to love about a giant prehistoric train?

I want more train mechas! I was in love with the rumor that Kyoryuger was going to be about dinosaur trains.

G12 is nuts, but I never found Paleomax that great. It looks fin, but it's transformation was REALLY phoned-in. It just breaks apart and reforms in a way where a few simple hinges would have done. I know a lot of RPM zords do that, but this is the most glaring.

I like how it's head kind of looks like the original Megazord. Intentional given the animals used?

All I can say is at least it looks like a single, cohesive robot unlike final combos that involve riding the final mecha into battle like Zyuranger, Dairanger, OhRanger, GekiRanger, Shinkenger, etc.

Any likeness is entirely coincidental, or if anything just done in passing. There wouldn't have been any significant reason for the Go-Onger designers to homage Zyuranger. Using the same animals sure, but Abaranger used alot of the same dinos as well.
Ohhhhhh yes. This thing is one big giant cohesive badass. I find the G12 to be the of epidomy giant stacker robot insanity, which is why I love it.

I just find it weird that the head not only shares similar ear designs, but they "open up" identical to the original Megazord, and feature the triangle design of the Megazord's chest, a design not present anywhere else on the Paleomax Megazord.

It's not overt, but it's just really similar to be coincidence. Maybe because they thought Power Rangers would end before RPM the Sentai designers threw in an homage?

No I don't think so. Toei would have had no knowledge that at the time they were in the production stages of Go-Onger (a time when Disney was still going through Jungle Fury) that RPM would be the "final" season. It wasn't even announced until September 2009, a full year after Go-Onger began airing and subsequently finished, that RPM would be the final PR season.

Those mecha were designed far far in advance of them being brought over here. I can promise you they don't design mecha and homage things in the original sentai versions of these shows so that it pans out better in Power Rangers. There's just no way to plan that kind of far ahead production and make it work out. It's similar, and as I said it's not the first sentai which has used a dino motif for the whole show or at least one robo. But seeing as at that point there were only 2 full dino sentais some similarities were bound to be exist.

I love Go-Buster King as well, but one advantage to the BoJ G12 that I didn't know until I owned my own "G12" is you can actually pick it up by the waist and not be worried about the legs and backpack falling off.

Advantage 2 of G12 over Go-Buster King is no spear weapon. I hold spear weapons as the epitome of "we don't know what to do with these leftover parts!" This belief was cemented when I got into Mugenbine. I swear Bandai's handbook has to have a section stating "Don't know what to do with remaining parts? Make a spear/staff!"

Oh definitely. From the get go I assumed some of the Mugenbine design team had worked on Go-Busters. The spear always kills me. Especially when you form King. Since it's significantly taller than Great Go-Buster, with Go-Buster King the spear just dangles there with out anything to balance on. I have mine propped against the wall.

With G12 you get one gigantic package with everything in a place that makes sense. Perhaps the only things that don't being Kyoretsu-Oh's waist piece and Engine-Oh's V-Shield just being tacked onto the legs. That part seems a bit odd but everything else makes complete sense. I also love the inversion of the arms and legs from G9-G12. How Birca and Gunpherd become glorified ankles and T-Line and K-Line get swapped up into arms but are still in the same basic position that they were in for Kyoretsu-Oh.

This was always my favourite mecha from Go-onger. It's a mammoth-train that turns into a robot!