I have been covering Lightning Ventures for a while, the companies they invest in are solid
As for Fountain, their app was clunky but in the last month they have made huge improvements on the UX level .... for a team of 3 (used to be 1) ... they show great potential
when you invest in a company, you really invest in its founders ... I suggest you listen to Oscar (on Kevin Rooke pod) to get a feel of where they are and their future plans and most importantly their ability to deliver
Best of luck!