The Manga and Mecha book is nice for a number of reasons, not just its mecha. If you can stomach M&M combat, then go for it.
I remember Palladium Games made a Robotech RPG supplement that I owned but never got to use. In fact, I don't think any of my Rifts games made it to the point of using giant robots. Which amazes me, considering half the game is about giant robots.
You guys should play Rifts. I dare you. Just make sure Kevin Siembieda doesn't get your money and it'll be okay.