No. First, clients may be sloppy or may have alerts triggered if the IP doesn't fall into the right range. The latter has nothing to do with poor code quality. That's the problem with hijacking DNS, you've moved well beyond web browsers into all kinds of applications that are loaded with custom code that have completely undefined behavior from your perspective. For all you know, the DNS responses you've tweaked will make the user's software completely unusable until the whole thing is restarted.

Second, what do you do when the client is configured to require DNSSEC responses?