My observation would be that the usage you mention is common and acceptable in spoken/informal usage. But in formal or "careful" usage, it might sound a little out of place to some ears.
One slight point to bear in mind is that "like" isn't always analogous to "as": it is also commonly used to mean "as though"/"as if" (the latter are essentially synonymous, but "as though" is a little more positive). In informal usage, there's usually little ambiguity. But in formal usage, if you avoid "like" and instead opt for "as"/"as though"/"as if", this gives you the opportunity for a little more precision.
The other thing to bear in mind is that (unlike, say, "whom", which is overtly formal) "as"/"as though"/"as if" probably won't sound overly formal to most people if you use them in informal speech. So if you're in doubt, you could just use "as"/"as though"/"as if" and avoid "like" with this usage.