Hey, author of the book here. Obviously any comments on balance are going to be pretty biased coming from me - though it's been going smoothly in my home game for a while now, for whatever that's worth - but I thought I'd poke my head in and see if anyone had any questions for me. You can e-mail me at jaberwocky (underscore) slayer (at) hotmail (dot) com (where "you" means "anyone reading this thread"), should you have any questions.
In general, though, Enforcer's got a good feel for it, though he might be surprised when I finally have enough cash to start using the advanced components for various devices. Those can be pretty powerful, though in retrospect I was too conservative in pricing them. It's also been nice to see that the craft points rules (cribbed and modified from Unearthed Arcana) have kept me in acid flasks and fully-repaired bots without slowing the game down much at all. I know that was a major concern raised when I first suggested the book, so I'm pretty happy with how that turned out.
Hmm, there are a few ray-gun type things in there, though. You could take them out and still leave plenty of devices, I would think, but it would take some of the punch out of mid-high level Technologists. I'd be tempted to handle it by taking out a couple of particularly sci-fi-feeling devices (e.g., Dalyrimple's lucent lance, maybe the atomic discombobulator), and changing the description of any of the devices described as being rifle-like. There are still a number of devices that don't look like guns of any sort, though, and pack a credible offensive punch - like the worm gauntlet, which pushes someone through hostile planar territory to damage and move them at the same time. Those kinds of things you'd only find in a technology-using class that defaults to a fantasy setting. There's nothing that uses anything analogous to gunpowder and nothing that is explicitly referred to as a laser or anything like that (and only one weapon that deals "light damage", the aforementioned lucent lance).
More generally, though, I worked pretty hard not to use much in the way of real-world physics in the book. I think it gives the wrong feel to be quibbling about the amount of lift an aviatronic wing can actually generate and things like that, so if avoiding real science and its attendant conceptual problems in a fantasy setting is your goal here you should be happy with the stuff in the book. If you've got power armor and the like, assume it's not the tech level of lasers that would bother you - it's the overly sci-fi feel of it. I think these devices will be weird enough not to feel like too much of a sci-fi infusion.
Let me know once you've read some of it what you think, though!
Matt Kelsey