I have a single mount Spider holster, and I have a couple of LowePro lens exchange cases that I attach to the belt.
However, I rarely use this combo, for two main reasons - (1) I found that my lack of hips cause me to constantly be concerned about the belt sliding down and even possibly pulling my pants down with it (especially when weighed down with gripped camera + heavy zoom, plus 2 other lenses), and (2) I found it challenging to slide the pouches around to access them to swap lenses.
I would say #1 is a personal issue for me due to my body type/build. However, #2 may be challenging for you as well. I would suggest going to a local camera store and trying it out on the floor before purchasing.
I've been looking at a vest from TheVestGuy or possibly using a vest + belt system from LowePro or other vendor as an alternative. I know, I'm probably the only guy who just can't get happy with the spider pro belt, but it is what it is.