Maybe it's just me having poor luck again, but it appears like the hotend_offset_z value in the current version of Marlin provided doesn't do anything. I'm getting no difference in friction regardless of the value I set and flash onto the device. This also extends to printing, where the 2nd hotend is digging into the bed and giving the same bad results regardless of the setting (tried everything from -0.5 through -2 and -10 to see if it did anything, there was no significant differences).
I'm also having a lot of trouble with the general temperatures of the hotends. They seem to swing wildly regardless of what I try - stock PID, calibrated PID for hotend 1 on both, split PIDs with EEPROM enabled so each hotend gets its own PID. All give the same general result, 10-15 degrees variance on both sides of the target on both hotends w/ socks installed whether the blower fans are on or off. I didn't appear to have this problem before I upgraded to the DSE. I had to change some other firmware values for target time and variance because otherwise printing would never start as my hotends never stayed within 5 degrees of the target for 10 seconds.
Also possibly related to this, I'm still getting print failures. I'm currently printing via pronterface because of another issue, and prints randomly give the heating failed errors even though the temperature graph looked like it wasn't more than 10 degrees either way off the target when the halt happened. Only seems to be occuring when I'm doing prints with both hotends as I've successfully printed 3-4 hour long prints with each hotend separately.
Also possibly related to this is the touchscreen randomly halting with a "machine closing..." error since I upgraded to the DSE setup. Everything from the software side was fine on the 2S Single extruder setup, so I'm at a loss here now.
Also is there any way to get the tool carriage to stay higher on the Z axis when switching hotends and then lower to resume after the heat is reached? The pause is short I guess, but with how long mine take to heat up there is still a 3-5 second window of a hotend just sitting on the existing printed area and causing some issues, especially with the first layer even on the calibration print.