I've read sucralose can not be broken down by or absorbed into the body, at least not entirely
(15% typically accepted absorption rate). It should just pass harmlessly through the digestive system or urinary tract, but that may depend on your own ability to break down the molecule. There exists reports of side-effects from people who are apparently sensitive to it.
If that
[lack of absorption] isn't true, then that could be a problem, but even some of the anti-Splenda research I've seen explains that the chlorine in sucralose is bound by
covalent bond which tends to be stable.
If Splenda worries you it may be worth your time to conduct your own tolerance study. I did one myself and found that consumption of artificially sweetened foods negatively affects my complexion, so I avoid them.
While sucralose is an interesting side story in the extensive list of things worth worrying about, concerning the food supply and possible corruption of the FDA I think there are far more pressing matters to exhaust your time.
Start here.