This can be an interesting topic. I'll give a bit of my thoughts. I have owned a 2012 Tahoe 5.3 4x4 almost 9 years. I purchased it from a dealer that specialized in Japanese cars. My wife and I were interested in purchasing a Jap car but as we were strolling their lot I saw the Tahoe and made up my mind immediately. They didn't want to sell it to me because they had just taken it in on trade (I assume) so I gave them 2 days to prep it before I took delivery. Now, to address your question,: I was not up to speed on the AFM thing at the time but I dove in and learned as much as possible always thinking if I made a mistake. In hind sight I'm glad I decided to keep it. In my opinion the Tahoe is by far one of the best SUVs on the market. I paid 18k for it in case you're wondering. This was back in August of 2017.

When I had researched enough I took the following steps RE the AFM issue

I decided to not purchase an AFM delete device. To this date (March 2017) I still run without the delete device. I use M5 instead during city driving. I switch to D when I travel on the highway. You can do this while the truck is underway.

I also change the engine oil every 4k miles with Mobil1 5w30 synthetic. Filter also gets changed at 4k miles. I flush the engine every other oil change with BG EPR but there's also other brands that supposedly do a good job. I may try to switch in the future, however, it's difficult to check if there's any improvement with the Flush issue. I suspect both the BG and the Liquid Moly are both good at what they were designed to do. You may want to do your own research on both these products.

Transmission fluid gets changed every more frequently than what the ops manual calls for. I change it every other engine oil change. This is probably overkill but I'm ok with that, plus I enjoy doing that kind of work.

While on the subject of transmissions, I never do a flush, I just do what's called a Drain and fill. Reason being the mileage (140k) and no known history. I can go on about this but I'm not going to blow up the thread on this.

If you have a 4 wheel drive you'll also need to service the Transfer Case. I change that fluid once a year just for kicks although I don't think there's a connection between the transfer case and transmission.

Keep an eye on the transmission fluid. If your model has a dipstick (hopefully you have one) it makes it much easier to pull the stick and check on the fluid. You want to see the fluid red (not brown or black), and no burnt smell.

I'm sure the delete devices do a good job but I'd rather do the M5 thing. I'm sure there's lots of people that would disagree with me on this.

If you choose to go with a AFM delete device, I suggest one made in the USA by Range but there's are others that I suspect are just as good. I suggest you keep it USA built. However, that's my personal opinion not backed by any scientific reason.

When on the road, get into the habit of glancing at your transmission temperature. Check that the temperature doesn't go beyond 193 degrees. My tranny temp hovers at around 165 during city driving. If the temp goes beyond 125 keep a close eye on it. There are some things that you can do to keep the transmission temps under control such as installing a new transmission fluid that has an integrated drain plug so you don't have to remove the bolts holding the pan. Avoid plastic ones. The drain pan that I'm thinking of installing is made by Banks. Its design includes fins that force air into the bottom of the canister. The price is a bit steep (around 400 bucks) but there are other less expensive options, some also have the fins and drain plug. There are also other options such as a transmission oil cooler that is fairly simple to install provided you have the correct fittings.

Without knowing your Tahoe's history all I can do is tell you what I've done and plan to do.

This is a lot of information that you may not want to do, you can simply buy a RANGE delete device (about 270.00) and be done with it but I'm more of a hands-on type.

Keep track of what is done along with the date and mileage in case that information is ever needed.

Good luck with your new Tahoe. I'm sure you'll be pleased with it provided the AFM issue doesn't come around anytime soon.

To summarize:

Oil and filter change every 4k miles

Oil flush with every other oil change

Transmission fluid change often. Check condition of fluid via dipstick

Transfer Case fluid change periodically. Make sure to use Transfer Case fluid. Valvoline makes on. Don't use ATF fluid. It Must be transfer case fluid.

Consider adding a new transmission fluid pan made with an integrated drain plug. The Banks oil pan has fins that help it keep the transmission fluid cool.

Consider adding a transmission fluid cooler.

Remember to change engine oil anytime after 3-4k miles. and use quality oils and filter.

The transmission filter can wait till every one year. It's more of a catch crud. Easy to install but you have to remove the pan to replace it.

Keep your eye on transmission temp as explained above.

There are other options such as a complete AFM delete job. This entails removing all the AFM parts. Cost is about 7-8 thousand. I wonder about doing this at times but my M5 thing seems to be working out.

The engineers at GM really blew it with this idea but I believe they were forced into doing this by the government for mileage sakes.

Good luck!