Mine is sten converted. It works well. As far as having the conversion done, its a bit of a toss up. The big pro of the conversion is to be able to use cheap sten mags. This was a big advantage under the AWB that banned the manufacture of mags over 10 rounds. That has gone away and people can now make M11 mags. So if you can find someone who makes them, I don't see the reason to do the conversion.
Sten mags are also really hard to load without a loader. Because they are so cheap, I just load up a bunch before I go to the range. I have five of the 50-rounders from Bust Off -- God they're huge -- look like a big monopod. I don't use them all that much though. They are a lot cheaper than a drum.