I don't have those with the reservoir, but have been running their shock with rebound as well as their fork cartridges for a few years now. I have used ohlins on previous HD's as well as other brands. I have also used Fox and Ohlins on many dirt bikes.
I think the Fox shocks I am currently running work great. In my opinion the reservoirs are overkill for HD's on the street. From my understanding the big benefit for the reservoirs are for long term rapid bumps to help keep the oil cool. Unless you plan to often ride on washboard gravel roads or similar I don't see the benefit, but they certainly won't hurt!
I live on a gravel road, but the closest I feel I came to possibly needing reservoirs was 14 miles of dirt road construction a few years back going around the Grand loop in Yellowstone. It was pretty rough, but every time we came to flagger to stop I was actually enjoying it, but my buddy was cussing and quite unhappy when he pulled up next to me.
The Fox shocks as i understand it are one of the best you can get currently for the side-by-sides for off-road racing. You may as well get the FOX fork cartridges while you are at it!
Best