The P365 doesn't do anything that other guns before it were already doing. The Sig name, marketing, and support simply made it popular. A smaller and lighter 10+1 micro 9mm with serialized chassis predates it. A small striker-fired micro 9mm with a removable serialized chassis predates it as well.
I do own a Hellcat and a S&W M&P Shield Plus, but I still choose a revolver and a traditional subcompact double stack. The Hellcat is something that I carry when I must have something smaller when I need deeper concealment; otherwise, it stays home.
FYI: The Hellcat is essentially the same size as the P365, but it's slightly lighter than the P365 and not the other way around. If not for getting a MUCH better deal price wise for a Hellcat over the P365, I'd gone with the P365. The Hellcat is cheaper than the P365 and has an extra round. I was able to pick up my Hellcat with optic cut with 6 magazines in total because of the Springfield "Gear Up" promotion for a couple of hundred less than it would have cost me to have a P365 and 6 mags in total.
The major reason why I give the P365 an edge is because Springfield Armory has a corporate policy against selling factory spare parts to consumers or third party vendors. If you need a simple spring or the like replaced, you require you send the entire gun in. I like to keep a lot of spare parts on hand for EDC guns I plan on carrying and using for many years to come. I don't want to have to ship one of my primary guns off and be without for a month when I can replace the part myself in 5 minutes or less. I also want to be covered if the model is ever discontinued. For all the aforementioned reasons, I would recommend the P365 over the Hellcat unless you get a killer deal or it's not going to be a primary.
P365
Length: 5.8 in
Height: 4.3 in
Width: 1 in
Weight: 18.5 oz
Hellcat
Length: 6 in
Height: 4.25 in
Width: 1 in
Weight: 18.3 oz
