Hi,
About Undertaker, why not just delete lines where it appears on context-2? Just keep
skillbar-4="190340" in your XML and delete all other occurences. But using Undertaker ONLY when you don't have Tombstone or Moonshine available is a good behaviour
You should keep that for PvE. You want to disable it for PvP purpose? If yes, try fusing Undertaker and Scorched Earth (
<condition skill="190170" variation-id="1" /> ) conditions to only display Undertaker only if you're PvE.
Why using boosted Darkshot, meaning you have selected Cold Blood + Dark Abyss (for PvE, you WANT to use this) instead of Medium focus Bullet Storm?
1. In this case and according to unstuffed description, Darkshot (Cold Blood + Dark Abyss) + Undertaker combo deals more damages than Medium focus Bullet Storm (and, of course, than Low focus Bullet Storm). You should use Undertaker during Light Speed (Light Speed is the phase where you can use Bullet Storm) because it will NOT affect your Dark Light during this phase and it will add substential damages to your Darkshots (and it anicancel very well). That's why Unload is useless during Light Speed too, because its own damages are low and will NOT help you sustaining Light Speed. Keep Unloads when you're out of Light Speed.
2. Bullet Storm is consuming a LOT of focus (15), so if you cast Bullet Storm, you will have to reload to much times during Light Speed phase that'll make you DPS very bad... In other words, you want to use Bullet Storm ONLY when you have infinite focus: Tombstone or buffed Moonshine.
3. A lot of gunslingers disable Bullet Storm because DPS between buffed Darkshot + Undertaker combo is near to Full focus Bullet Storm. Okey, a Full focus Bullet Storm burst is the best way to DPS, but they lose DPS as soon as Medium and Low focus Bullet Storm are casted because they don't have choice when they enter Light Speed phase without any infinite focus buff. By editing XML, you can get rid of Medium and Low focus Bullet Storm, so you can really perfect your DPS this way, optimizing the original mechanic of Undertaker Gunslinger.
So you like editing your XML
I've some more advices to perfect your rotation and I could give you a special XML where the DPS rotation is totally optimized. I can help you for Destruction spec, for Summoner (both spec) and Warlock (both spec).
But maybe you want to do it by yourself if it feels funny (I do). So here another "general" advice for XML editing: use at least 2 keys to macro your DPS (yes, you can have multiple working "Simple Mode" keys, it's not bound to Right Mouse Button only). Modding Left mouse button + Right mouse button is maybe the best way, I think.
Why doing it? It will help you a lot for optimizing anicancelling or when you have to cast multiple skills at same time. You could, for exemple, display your DPS on LMB and force to display other interesting skills like anicancels, in some conditions, to RMB.