The actual 1.17c patch is under 1 MB at most, according to estimates. This is why:
All of the last ones here are all part of the same "Patch 4" since we haven't reset the timer to start again (as per the only 4 files I downloaded on fresh install)
D2011.05.19.0000 328mb <--- 1.17b
If it keeps up like this, every dam patch will get bigger and bigger, taking longer to download and the patch system is horribly unorganized beyond what I thought it was before :(
I guess they want the patch sizes to be EPIC, but really, this last set of updates totaling 336mb should have been as follows:
much easier to download :(
As it turns out, 328MB is also the size of today's patch.
So, that means there's roughly <1 MB of data different between 1.17b and 1.17c, you just get the pleasure of redownloading that and the last 9 patches before it as well.