Both of those settings might be somewhat problematic with stock EBS volumes. We run everysecond and very frequently see "Asynchronous AOF fsync is taking too long" because EBS can't keep up. The problem is when that happens Redis is blocking connections and exceptions pop up from the clients.
A work around so far is to sync every 60 seconds on the master, and more frequently on the slaves. Another option might be to bump up the IOPS on the volume, but I believe that still isn't available on medium instances (which we are using as well).
While many Rubyists may use a Mac I'm confident the large majority deploy those applications on Linux. Cross OS compatibility issues are virtually non-existent, especially on non-development focused gems.
Great plugin, although it's ability to jump to the next empty tag was overriding with my tabbing/completion(probably conflicting with SuperTab) - so I remapped that functionality to Ctrl-i rather than Ctrl-n:
let g:sparkupNextMapping = '<c-i>'
So far that doesn't seem to be conflicting with anything...