I'll throw in my 2c
I THINK the malossi cases have more volume/larger intake compared to polini and are more ment for 70cc kits like the description states (maybe someone more knowledgeable could chime in about this).
The polini cases do offer IMO a nice mounting system and easy to adapt engine spring (don't need the plastic engine spacer doo-dad's). The malossi cases have a wider case bolt pattern so you can't just drop in the polini spring set up (unless you are using stock spring then they both work fine).
Here are the transfers, one is a stock and polini side by side and then malossi. You can see the malossi case have more meat to open up if needed.
Let us know what ya end up using!