Re: Dimarzios for mahogany prs
Based on the EQ curve, the Transition looks like a beefed up Norton with a bit less bass and treble. This should give you a good metal sound.
I have a Norton is a mahogany RG and it gives a really nice and tight low end with a lot of clarity for power chords and other rhythm stuff and is then rolled off somewhat up top. Consequently I don't like it as much for lead stuff as I do the PAF Pro or FRED, but that's my personal preference and those aren't really metal pickups anyway. I think you'd probably really like the Transition for what you want.
I have the Liquifire in the neck of the RGT and I absolutely adore that pickup. I also really like the Air Norton in the neck and feel that the Liquifire does an even better job there. But again, I'm not using this for metal and I find that the Liquifire gives a really nice fat, warm blues sound in the mahogany and maple RGT. Might not be what you're looking for.
If you weren't a huge fan of the Liquifire, perhaps you'd like something with a more balanced sound like a Gravity Storm neck or for some more oomph, a Breed neck? If you can explain what specifically your issue was with the Liquifire, I might be able to make a better suggestion.