I only nomintate or vote when it's a book I will read within the next two months. This month that meant I nominated two books and seconded one. That makes it difficult for me to support many of the books sometimes. But it's an accurate assessment on if I will be active in the discussion which is what I think we all want in the end. A book that as many people as possible will read and discuss.
As far as e-books. I don't have access to library e-lending in Canada with a Kindle, but that hasn't stopped me from borrowing paper copies for the book club previously. Yes, I have an e-reader, but it isn't my only option for reading. Budget, availability and wanting to own all affect how I choose to read many titles. Right now e-books count for about 30-40% of my reading. If anyone doesn't want to nominate or vote for a book not available in e-book format, that is their choice.