Ditto on the 40mm pancake.
I'm using Microsoft ICE
to stitch with, takes CR2s as input, I take output as tiff though I'm sure there are other choices.
RSS angle bracket, level tripod head base and QR plate, nodal rail, 6D in portrait, auto rotate switched on, full manual exposure and focus, live view or tethered live view.
I eyeball overlap about 2/3, recent sets have been 13 frames for 180 degree coverage. ICE stitches such a set in less than two minutes (on this hardware, YMMV), if I've corrected for parallax, lighting is consistent and nothing moves, I see no artifacts.
I have PSE 11 and GIMP 2.8.10, neither can deal with 16 bit color.
I have stitched jpgs in PSE, results were ok though the file size was quite large compared to ICE's output from raw input, that puzzles me.
8 bit, 16 bit, I can't see the difference, but, conceptually, gotta have 16 bit.
On a lark, I tried a handheld pano sweep in burst mode, got a lot of parallax error artifacts. Deleted all. Learn from failure.
I tried Canon's Photostitch, it stinks, totally garbage. Resolution was destroyed, obnoxiously obvious artifacts, just awful.
What is your pano workflow?
I'd especially like hearing from Sporgon. .