Closest to using both was having both resellers come into my place and do a demonstration on two of my parts.
Each took me 6 hours to program, proof and tweak by hand.
Gibbs guy spent 20 minutes or so on each to produce a working programs, while explaining to me how he was going about it.
MasterCam guy started over several times trying different ways to tackle as each way had a little issue that did not produce a working program. After about an hour I realized I did not need all the Bells and Whistles that came with the program...at that time. I bought Gibbs, made many thousands of great programs with it over the years...but now after 10-15 years of using I am starting to feel, maybe masterCAM would have been a better choice.
In my opinion Gibbs has gone downhill since it was bought/merged with 3D or whatever with they did. Every year more and more glitches with each release.