re: the catch
I already use Gmail, and have learned to completely ignore their "sponsored links" ads, etc., on the right-hand sidebar. [Though I have to admit, when they do catch my eye, they are often hilarious, depending on which keyword they've focused on in the thread.]
It'll be an interesting exercise to see [a] how they appear within the X-CAD ap' itself, and [b] whether they can be blocked with my resident firewall.