I did notice that! I don't use a travel power. I actually don't use it on many ATs anyway because of Ninja Run, but yeah Shinobi-Iri is nice all around.
I've lost some of my love for Suppressive Fire. I keep it, but it has less use for me when running Ammo which I've done since I unlocked it at level 8. Since Suppressive gains no added damage it takes a back seat, and the hold just isn't long enough for me to care.
There is something to be said about turning ammo off and using the default secondary effect, but I feel no need to do it. If you run normal Ammo, Suppressive's DPA is actually better on paper and makes it more worth while to use. Incendiary Ammo makes everything else higher though Dual Wield vs Suppressive is a bit more competitive vs it being a washout. That's without considering proc opportunities which Dual Wield can win on. One of my build ideas stuffed procs into DW and it had a lot of potential.
This got me thinking though. Suppressive's DPA isn't "bad". Especially for normal ammo. In fact with normal ammo Suppressive's DPA is better than Piercing Rounds and Dual Wield (substantially more so for the latter). So maybe I need to see if a Pistols -> Suppressive -> Pistols -> Executioner or Pistols -> Executioner -> Pistols -> Suppressive would be better with normal ammo. For most things not a Boss, that answer is probably "yes". That chain loses out on the normal Ammo resistance debuff of Piercing and the potential debuff of Annihilation. So it is likely the faster attack chain won't be better against Boss+ since on normal ammo Piercing is a guaranteed -9.6 resistance (assuming none of that is resisted by their resist value, which it will be for AVs).
However, if the powers that be did allow Suppressive to gain damage from Incendiary Ammo, it would be a buff to that power and make a a quicker animating chain likely better in all situations unless you really needed that resistance debuff (so virtually only EB/AV). I'd love for Sentinels to have a unique attack chain for DP vs what everyone has. Suppressive Fire has the potential to do that, especially with normal ammo, but those debuffs in Piercing Rounds are strong reasons to keep it as a priority power.
I doubt I'll change where I'm at with my build right now, but these are definitely things to consider. I also hope it is obvious I am just thinking out loud, and that this thought process is aimed at pretty tough targets. My build has all the DP and Nin powers. In actual play, I seriously do use all of them. I open with Hail, and follow up with Bullet Rain/Empty Clips. With Incendiary running virtually 24/7 since it removes the knockdowns/backs which I personally don't care for in favor of the damage-over-time element. For clean up, I just fire off the fast attacks like Pistols, DW, and Suppressive. If an enemy has a sliver of health left, I don't shoot them with an Executioner's Shot (no matter how fitting that is) and just hit them with Pistols.
The only time a "real" attack chain really matters is against targets tough enough to survive the sequence in the first place. Otherwise just cycle what isn't on cooldown and pepper everything with follow-up shots.
Slap the Purple Hold Set Proc into Suppressive Fire and it looks like it pulls ahead of Piercing Rounds in Fire Rounds. PR cab slot a -Resist Proc however, but I'm not sure how much DPS that will add in the long run.