That could, in theory at least, be an advantage if you have a good process for capturing and storing that offgas (reacting it with something to make it solid and then glassifying it, for instance).

In a traditional fission reactor, gaseous fission products cause swelling and cracking of fuel pellets, and builds up pressure in the fuel tubes, which is one of the factors limiting fuel burnup.

Well, a lot of 'common MSR talking points' are overblown, firmly detached from reality. Or at least conveniently ignoring all the significant challenges remaining in industrializing MSR technology. MSR fanboys are the most tedious of the pro-nuclear side of the energy debate, perhaps beaten only by the "this entirely unproven aneutronic fusion concept will imminently solve all our energy woes" crowd. :)

Some other things that you really don't in your fuel, like Xenon and Krypton will bubble out.

So I think overall it is an advantage.