Depends on the witch hunter you are playing against.
As far as I see it, most people have no problems with round bases, as long as you do not get too unreasonable yourself - like insisting on a human-sized model's not being able to be charged because of the roundness of its base &c.
There was also a stickied thread on round vs. square bases / -ing somewhere here on these forums, but I cannot find it at the moment ...
/Edit: Ha! Resources section: Here