On a happier note, Flint will have at least 5 more 163x novels coming out in the next few years (with collaborators, of course) plus a couple more with Carrico & Spoor. So even gone, he’ll still be keeping us reading. It also sounds like there is hope of a new controller to keep the 163x universe active and on track.
I’ve not read these yet even tho I have them. Can anyone compare them to the Castaways In Time series by Robert Adams? I recall those being light but entertaining reading. Are the Flint books a more serious take?
Yes and no. Anything with Flint’s name on it will be pretty straightforward alternate history. Other authors might take a different approach. The “Dr. Gribblefrotz” books are on the lighter side, but still hold true to the overall concept. They are much, much better than what Adams cranked out.
Excellent. From reading your posts I think we have similar tastes in reading material so that’s good news. Well, except for you liking Pratchett. There is no rational excuse for that. 
Now I just need to find more time to read, I have umpteen unread books.