Thanks for the advice. For me, I'm not so sure the stipend difference is negligible. It amounts to a bit more than a 200$ difference a month.
I've been in contact with both graduate directors but that's it. Both departments look good, although Clemson seems to have more staff from big-time schools (eg, many out of Chicago). I studied for a semester at UT so I have some familiarity with the area.
The recent placements of both programs, frankly, are not all that different either, which is interesting considering UT's absence from major rankings. Clemson's placement record might be ever so slightly better, but the difference is pretty small.