The new source will be bringing us the v72 skill table (with some v86 skill changes). Let's assume that there are no v86 changes to Shadowers. Will the v72 changes be considerable enough to where Assassinate+B-Step Macro > Meso Bombing? This is also considering that the Shadower macro'ing is maxed out skill wise and is funded (lets use @Marty as an example? =p). Spoiler This is for bossing btw v72 / v86 Skill Changes: http://royals.ms/forum/threads/possible-skill-changes-in-game-post-new-source.24684/ ( @Plenty )
Seeing as Nexon even considered to decrease the cooldown time even more 13 patches later for Boomerang Step, I think it's safe to say that Meso Explosion is still a bit better unless you're extremely funded.
I was already out-DPSing ME on Heartstoppers and going about equal on Energizers. That is with a 8.5k clean range nearly. We'll have to wait, though. The decrease is significant (I believe down to 1.5 seconds or even 1.2 instead of 2 right now), but since the new source code is promised to be lag-free, I could imagine people dropper even faster. I personally would be able to drop up to 15 bags a second for a while without macro (30 clicks/second), so if the new source code would allow that, then ME>Bstep+Nate again. It should really be looked at on a case-by-case basis for each Shadower, depending on how fast you drop and how fast you could drop without lag.
It sucks that ME is depending on the amount of mesos, I really liked playing when even coins did full dmg and BS + savage blow into ME was the best combo.