First off, SourceForge isn't me :) I just run one of the largest projects hosted on SourceForge.
Second, Github doesn't really offer what the big binaries on SourceForge need which is tons of bandwidth to host downloads. Github ditched downloads back in December but appears to have added them back in with 'Releases' last month. It remains to be seen how much bandwidth a free and open source project can actually push through Github, though. And whether Github will keep Releases/downloads around at all since they've only been around for a month and were unceremoniously killed off just 8 months prior.
SourceForge is a known quantity with download mirrors all over the world that you can push 10s of TBs per month through for free as long as you're a fully open source project. Github, on the other hand, is an unknown quantity with respect to big downloads.
Second, Github doesn't really offer what the big binaries on SourceForge need which is tons of bandwidth to host downloads. Github ditched downloads back in December but appears to have added them back in with 'Releases' last month. It remains to be seen how much bandwidth a free and open source project can actually push through Github, though. And whether Github will keep Releases/downloads around at all since they've only been around for a month and were unceremoniously killed off just 8 months prior.
SourceForge is a known quantity with download mirrors all over the world that you can push 10s of TBs per month through for free as long as you're a fully open source project. Github, on the other hand, is an unknown quantity with respect to big downloads.