Seen them both, used them both, six of one, half dozen of the other. I put this in the same category as which airbrush is better. You like Iwata, he likes Aztec, I use a Paasche.
I have a 4" Hold & Fold and it works well for me. There are some changes I'd make to it if I were king for a day. The EtchMate looked like a higher quality produced tool though, but I like the compact size of my little H&F. Not saying my H&F isn't high quality, the EM just looks like it was factory produced while the H&F looks like it was locally made.
Disclaimer: The above observations are just my personal opinions and not representative of any modeling website I may frequent. I state this in case the manufacturer, distributor, inventor, retailer, advertiser or immediate family member of the aforementioned entities decides to e-mail any nasty-grams to me regarding my thoughts on the above mentioned tools. Any attempt by said parties to drag me into the middle of the EM vs. H&F feud will be ignored.