I have both. Isspro analog on my 91. 5 W-250 & X-monitor (pyro & boost) on my '03, 3500.
The only reason I went with the X-monitor was because I did not want to remove the grab handle. I was able to get multiple guages in a single pod that mounts under the handle. Best of both worlds.
I didn't want to put the guages in the cubby hole because I didn't want to take my eyes off the road to look down at the cubby hole. I, often, drive mountainous roads with my travel trailer and that seems to be when my engine is working it's hardest. That's when I want to be monitoring what's going-on.
However, I think I like the analog guages better. As others have said, you can just glance at them and know if your in trouble, or not.
Joe F. (Buffalo)