I'm actually looking at this type of configuration, at least initially.
It's all about WAF. My existing Linux setup has had a few issues and, as I work away, the family have been left with no internet. Not good! The problem was actually with my router, but that's another story! I ended up taking my Linux server out of the link and allowing the home PCs to connect directly to the router.
My plan is to add my core to the existing network and begin with my MDs etc behind it. After much testing, I intend to move the kids PCs and the portable devices (iPod touch's, PSPs etc) and then, if there seems to be a tangiable benefit to doing so, my wife's and my laptops.
My wife is very IT (but not Linux) literate and gets very frustrated when something goes wrong and she can't fix it directly herself. Until I have established exactly how stable MCE is, I daren't risk her internet link