I have 2 Hellcats, one with the stock Tritium sight and the OSP slide with a Swampfox Sentinel red dot mounted on it, the other with no red dot and aftermarket Tritium sights. I put the Hyve magazine extension on both of the 11 round magazines that came with the guns so they now hold 14+1 rounds. I have put about 1000 rounds through each of them.
Here's a few observations. 1st, the trigger is fine as it is. There aren't any real problems with it functioning well and consistently, but like any trigger, it has it's own unique feel and I did find I was more accurate by moving my finger placement to more of the tip of my finger than I was used to. This kind of thing probably varies from person to person, but time spent on the range is what you'll need to get used to it.
2nd, the metal bodies of the 11 round and 13 round magazines are identical with the exception of how many holes are drilled in the back so you can see how many rounds are loaded in them, so it doesn't matter which one you add the Hyve extension to, they'll both end up with 14 round capacity. The Hyve does add a little bit more length to the grip over the regular 13 round extended grip, but not much. But, I haven't really seen any micro compacts with extra long grips, it kind of defeats the purpose of making it extra compact. If you have big hands, they are all going to feel tiny to you. I have some issues with arthritis flaring up so I also wanted a grip that was long enough to get all of my fingers, including my pinky, securely on the grip and that was a big part of why I picked the Hellcat over other guns. It seemed to have to longest grip of all the micros. That being said, I have pretty average size hands though.
3rd, the only safety on the Hellcat is the trigger safety. Personally I like that. For me, the less things I have to think about in a self defense situation, the better. I always carry mine in really well made and secure holsters with trigger guards and spend a lot of time training to draw with my index finger extended on the side of the weapon. But, that may not feel comfortable to you. If it makes you feel uneasy to carry something like that, you'll be less likely to want to carry it at all and end up leaving it at home most of the time. That's just going to be a personal choice only you can make.
4th, it's a 3" barrel and kind of snappy in the recoil department. I can nail tight groupings in typical defense situations at 5 yards or less, but I'm not going to be taking any hero rescue shots at a suspect holding a hostage across the street. Micro compacts have their limitations, so understanding that is a critical element when selecting one. The Hellcat is very accurate in itself, but I'm not good enough to nail 25 yard shots consistently with it. Understand your own limitations before choosing to carry a gun with a 3" barrel.
5th, having 15 rounds in my gun gives me the flexibility to put multiple shots on target when the situation might arise without feeling like I have to really focus on conserving ammo. 7+1 might sound like enough rounds until you run into 3 big guys wearing leather jackets working together to rob you and all moving at the same time. It might take 5 shots to stop just one of them or you might put an end to the situation with 3 rounds. Extra capacity makes me feel a lot more secure and that was a huge part of my decision to buy Hellcats. If you carry an extra mag, you're not going to run out of ammo anywhere. Ok, well maybe if you find yourself in the middle of the zombie apocalypse.
6th, one of mine came with the red fiber optic sight. I'm a professional musician, a drummer, and the places I run into sticky situations are usually at night when I'm loading my equipment after a gig. Most of the time I have a whole band out there with me, so there's enough people around to deter anyone from trying anything, but frequently, I'm in a dark back alley loading stuff by myself. In those places, the fiber optic sights are useless. If you buy a Hellcat, get one with the Tritium sight. Trust me.
7th, Red dots can be a help or a hindrance, depending on when, where and how you carry. They can increase speed and accuracy if you train a lot with them, but they can also snag on clothing or slow you down considerably if you haven't spent a LOT of time practicing sight acquisition with them. They aren't as intuitive as you might expect. If you are used to them and like them, bingo, there's a Hellcat for that. If your idea of training is watching a YouTube video, they'll get you killed. Bottom line, if you buy anything new, plan on spending a lot of time practicing with it.
And last, but not least, it's called a Hellcat. Seriously...What else do you need to know?...lol
Hope that helps some.
JA