Rusty,
For me it is a matter of logistics. The nearest reliable source of dry ice for me is over 20 miles from my house and they are only open during the week, typically 8:30-5:00. Next closest source was a Walmart, but they took it out a while back. So ice jugs it are.
As far as environmental, it is basically a wash. Most dry ice is produced using CO2 that is a by-product of some other process. We used dry ice blasting at work occasionally and I have had to write the environmental impact statements for the projects. Where we come off like the shining stars is that the dry ice blasting replaces a whole host of chemicals and residues that require special handling, with the dry ice blasting typically all you have left is whatever you were blasting off. Prior to switching to the dry ice blasting process we were using a lot of chemical cleaners that were high VOC and in many locales were outright banned.
If you have ready access to it and the cost doesn't bother you, go for it.
Aaron