I use standalone/direct-download version, because for a tool like iStatMenus, you don't want it sandboxed and unable to access system-level stats. I prefer App Store versions of software, but exceptions should be made for these types of utilities. This might be why you're not seeing new sensor data.
Then again, even though I'm running the standalone version, I was only seeing the SSD sensor for a while too, and then suddenly it auto-updated and I was able to see much more. The fact that you're able to see that sensor already means this might not be a sandbox/AppStore limitation, but the fact that their updated version hasn't gone through AppStore approval yet.