To give some context on what I think should be allowed, here’s my Hagah builds:
Personally, I think these stay in the spirit of the Hagah aesthetic, while addressing some of the weaker parts of the existing Hagah sets. Needless to say, I think these types of customizations should be allowed.
And although I didn’t choose to do this, I think some variations on the Metru body should be allowed like Kodiak’s Bomonga. I also think that custom torsos should be allowed, but they should have the same approximate dimensions as the Metru gearbox.
Ultimately, each person is going to have their own personal opinion on where exactly the line should be drawn on what should be allowed to be canon. Because Greg never gave us a rigorous definition of a “Metru build”, that line won’t be objectively drawn until after the contest and Greg approves it.
In the spirit of (1) letting the community as a whole have a say in what defines a Metru build and (2) keeping the rules fairly simple and keeping this a fun contest, I think the rules should allow for a large degree of customization. If you are concerned that the community won’t “respect the canon” in their vote, remember that Greg has the right to veto any potential winner. If he doesn’t think it matches canon, he won’t approve it.