He is definitely gone. I was just looking through some stuff last week and found a hand written letter from him stuck in one of several Porsche books he sent me, yes, he was a generous guy. I also still have emails and PMs from him telling me about his cancer returning, my replies offering support, etc. He had a serious and deadly form of cancer and had the means to get treatment in Europe that was not available in the U.S. or Canada, he told me quite a bit about it. He disappeared off the radar soon after telling me about the relapse, previously he would never take more than one day to respond to any message no matter where in the world he was.
I've been fortunate to be around plenty of smart people in my life and yes, he was a high quality individual. His kindness was so much more important than his intelligence or accomplishments, those are easy to come by in some locales. Shortly before he went away, he was still looking at Porsches and called me about a 356 roadster in Toronto he was looking at. A Porsche man to the end.
He was someone I really wanted to meet in person and looked forward to hanging out with in Europe. My brother has a place in south France w a very famous lawyer as his only neighbor, I had visions of inviting Mark up from one of his times spent on the Riviera, (remember his story about the lunch at the Russian oligarch's house?), and chilling out. Sadly, not to be.
Life is short, make sure to live it. That means different things to different people, make sure to make it your own. He enjoyed his time on earth.