I've been reading here and there issues with the 6L80. You would think the 80 means heavier duty. I'm getting the impression that it's not. From what I've read, yes a 4L60 would be more dependable the a 6L80. The 6L90 I've not seen this issue.
Please do some research on the 6L80 vs 6L90 before you pull the trigger. Could turn out to be very expensive if you don't.
Also, with a Gen V engine, are you planning on doing an AFM/DOD delete or are you going to leave stock? From the kits I've seen, that could run $1,000 and up depending on used parts. Just a heads up. If you don't convert, you run the risk of the lifters failing costing more possibly.
The above info has actually stalled my want for a 6L80 any time soon in my truck.
Again, please research plenty for your wallets sake lol. Create a spreadsheet with all options and possible failure costs (due to known issues you'll find on the web) later down the road.