I got a text earlier today stating that my $19 music pack was getting 50% more data from 500MB to 750MB.
Looking at the Spark website, it seems they've upgraded both $19 packs to 750MB and the $29 pack to 1.5GB.
It's a pretty timely move, as I was starting to seriously consider what the competition is offering. The increase in data is enough to keep me with Spark for the time being, especially with Spotify Premium.
I do think Spark need to have a look at upgrading the $39 open term plan though. With the current prepaid upgrade, the $39 plan is pretty poor value, unless you REALLY need the extra 100 minutes, and/or Netflix is a factor.