The Cirrus does use a "wet" wing.
It is wrong to draw conclusions from such a small sample, however, In my view the reason for the apparent increased incidence of post impact fires in Cirrus is that the tank is entirely fibreglass/GRP, unlike for example the Diamond tank which I understand is a conventional aluminium tank contained within the wing.
I think there's a little more to it.
First, there is the difference between a wet wing and a separate fuel tank contained in the wing, regardless of the material. If you have a wet wing in a crash, it is almost certain that the tank walls (ie. the wing surface, leading edge, spar) will take some or all of the impact forces. If you have a separate tank within the wing, the tank walls will only be impacted after the wing itself fails. I think this is inherently safer, regardless of the materials used. See double-walled oil tankers (ships) who have replaced virtually all single-walled oil tankers after the Exxon Valdez drama. Installing fuel tanks also gives the designer flexibility in offering different fuel tank sizes, like on the Diamond the long-range tank. But it has an inherent penalty in weight.
Second, there's the material that the tank is from. Slippery ice here, since aluminium and GRP/composite have different strength characteristics and depending on who you talk to and what loads are considered, either of the two can come out best. To me, what makes the most difference is the behaviour in fire. I think an aluminium tank will stay intact until reaching very high temperatures, after which it will melt. A composite tank will lose a lot of its strength at much lower temperatures and as far as I know, most composites will actually burn, instead of only melting.
Someone also mentioned the Europa tank. This tank is made from rotomoulded polyethylene, which is completely different from GRP/composite or aluminium. It is very strong but melts very easily. In fact, when opening up the tank fitting holes the factory recommends using a hot soldering iron instead of sawing/drilling. But most importantly, the Europa tank is carried in the fuselage itself, in a location where even in case of a crash, there's not going to be a lot of impact.