No. If occasional borrowing means no, then I don't. My boss has one that I use once I get my guns grouping well and I feel happy with them. It may solve a few problems I've had with some of my picky rifles though. I don't shoot serious enough to "need" one yet, but I can see that changing.
I've never used one setting up my AR dope chart and backed into the chart by using JBM and actual field data. I shot more rounds doing it that way, but it has been spot on for elevations and shooting is the fun part.