Thanks Marcia, librarychick, and Arianwen for your responses.
librarychick -- we really did try a lot of those methods, for a period of about 6 weeks. I know it's not a long time, but for an 8-month old growing kitten, it was long enough for us to come to the conclusion that he simply wasn't eating enough daily to meet his requirements. Almost overnight, he seemed to stop eagerly gobbling down the food he'd once loved (we did have a vet checkup to make sure it wasn't a health-related problem). Since then, we tried a number of different textures (chunks/ground/mince etc.), meats, combinations, and we always offer raw meaty bones a few times a week for his teeth. It wasn't that he didn't "like" any of these foods -- he'd always eat them eventually -- it's more that sometimes we needed him to eat when we were feeding him (or at least somewhat around that time). We're in and out a lot of the day, and couldn't spend 2+ hours waiting for him to decide he was ready to eat the food we were offering. Based on my very limited experience, it seems like one of the larger issues with raw food diets isn't simply whether or not it's best for the cats (lots of debate out there -- we're fans, personally), but how it fits with owners' lifestyles. Call it selfish or what have you, but it's a reality we've had to face as owners who aren't home all day and able to monitor feedings for lengthy periods 3+ times a day. The last thing we want to do is leave food out sitting and becoming harmful for him if he happens to eat it too late.
I'm happy to hear that you guys have had success with mixing, but the point about the habitual problem is well taken. I can see how it might be a slippery slope. He's eating like a horse right now, but if he gets picky again, we'll make sure not to switch to the "next best topper" to cater to his pickyness. These are all fairly new issues to us, as our previous cat just munched on his dry food all day (which we feel so guilty about, knowing what we do now -- we were just going on our vet's advice previously).
I was really just concerned with the general health situation when feeding a mix of raw and canned, and this doesn't seem to be too much of an issue based on my research and what y'all have said. Thanks very much to all of you for your input!