Which to buy? Tactix Delta / Fenix6 / Forerunner

The 6X Pro firmware is what is installed on a Tactix Delta. The difference in runtime behavior are very small and they must be from turning things on and off based on a hardware identifier that the firmware detects at runtime. Maybe it just reads the <Model> element from the GarminDevice.xml file at boot.  You can't access that file on the latest devices that use Media Transfer Protocol. 

Yes, I think it is most likely that the Tactix watch faces are in the fenix 6X Pro but just can't be accessed for product differentiation purposes.

The difference between a Tactix Charlie and a Fenix 5X was similarly de minimus, but the firmware was released less frequently. I wonder if the change to MTP means that they don't have to worry about people editing their device model and can simply ship one firmware instead of keeping a fork with special minor tweaks for the Tactix that they have to compile in. That potentially makes the Tactix cheaper and easier for Garmin to support and the result is it gets firmware updates in sync with the fenix 6X Pro.

I believe Garmin did consolidate firmwares hence a few months back the build version changed dramatically. 

Same issue in Canada, so hard to come by, ended finding a tactix on Amazon, not sure if that might work for you? Just trying to help if possible. I got a great deal on Amazon too! Good luck

Not sure if this helps but sharing anyway. I decided to upgrade from my 645M to the Fenix 6 last weekend (for the 2nd time). I decided once again to go for the Fenix 6 Pro Titanium/Ember to get the slightly reduced weight increase compared to the other Fenix 6 mid-size models. 

I decided the 6X was too large, and the 6S wouldn't give me the screen size increase over the 645M that I wanted which therefore put me in the mid-size 6. Then it was a decision as to whether to pay for the extra weight decrease with Titanium vs going for a black or darker version. Having had my new 6 Titanium now for 4 days I am very happy with it, it is a very nice step up over the 645M and I have already adjusted to the extra weight/size.

For me the Taxtix Delta was never a serious consideration as I prefer the standard Fenix 6 styling, but also didn't want the 6X size body. However it is very subjective so if unsure on what size to go for then only really option is to go to a store and try since photos don't really provide the feeling of wearing the larger watch.

You can see much more detailed comparison with the 645M on my earlier thread here: https://forums.garmin.com/sports-fitness/running-multisport/f/forerunner-645-645-m/172427/645-vs-fenix-6-comparison

The photo below is the 6 Titanium on the left, the 645M on the right - both with the Infocal watch face.

For me, the Forerunner 945 was never in consideration as it looks very plastic and the larger body with the smaller screen looks dated. I had originally planned to wait for the Forerunner 655 as I don't need multisport, but have got tired of waiting. Very happy with the Fenix 6 upgrade and glad I have it.

If the Tactix came in a Gorilla/SS variant for the same price as the F6X, I’d have gone with it over the Fenix just on looks. But for the extra £200 it was a non-starter. 

You can never have too many!

So my Tactix Delta officially arrived and I must say, I am as excited with it on my wrist as the day that I ordered it! It was worth the 5 week wait.

Small wrists - doesn't seem to be a problem. Overall the weight of the watch feels great, and it doesn't feel big on my wrist. And keep in mind, I've been a person who decided that wearing watches was not for me for the last 30 odd years. I was a bit dressed up yesterday when I picked it up, and it certainly looked the part. I definitely know I can pull off a suit with this guy, but also get into the middle of the forrest and bang it up.

Took it on my first run today, a nice slow 7.5km and barely noticed it was there. In fact, multiple times during the first day I forgot I was wearing it. 

To all my small wrist friends in this community (I have a 6 1/4" wrist), if you want this watch - don't be afraid of the size. It sits great, doesn't hang over the edges of my wrist, and feels comfortable. 

https://ibb.co/Lt9vcGg 
https://ibb.co/VDXTt1c 
https://ibb.co/VtngvTz 
https://ibb.co/n60SYNT 
https://ibb.co/k14vYkh 

Well done on the pics.  The watch does look much bigger on the turned wrist than on the mirror shots, same as me. Now get some decent watch faces.....lol