Co-founder of Catch here, some context; we launched our first Android app in 2008 and have about 10x as many users on there as we do on iOS.
The issue we've seen is that people build an iOS app and then port it over to Android.
We designed Catch 5.0 apps for Android and iPhone in parallel. This let us keep consistency between the platforms when it made sense, but also let us tweak the design early on so it could take advantage things unique to the platform, e.g. Action Bar on Android.
The team is incredibly proud of this release, and it is nice to see folks taking notice. Both Google and Apple have also featured this release, everybody is beaming here. =)
That's most people's findings. If your dataset can fit in ram  and you don't care about your data being safe then there might be an argument for MongoDB. Once you care about your data, things like Voldemort, Riak, and Cassandra will eat Mongo's lunch on speed.
I am sorry, to sound blunt, but that's an irrelevant data point. With a data set that fits comfortably into RAM (much less SSDs in RAID!), most any data store will work (including MySQL or Postgres).
> Operations per second: 450
Again, not a relevant data point. With a 10 ms seek time on a SATA disk, this is (again) well within the IOPS capacity of a single commodity machine (with RAID, a SAS drive, row cache, and operating system's elevator scheduling).
You'd think -- but the 10gen guys weren't surprised when we were struggling at this level (periodically), on a RS with two AWS large instances and relatively large objects.
Absolute ops/sec in and of itself is relatively meaningless tbh.