Looks like max 50GS/s per their site. That also looks reasonable with the screenshot they have in the article showing 1ns / div horiz. But clarity on the data would be lovely. =)

Actually I take it back: For the series 6B spec page... Real-time: 50 GS/s (2 channels), 25 GS/s (4 channels), 12.5 GS/s (> 4 channels) Interpolated: 2.5 TS/s