For modules that are premiered at the big conventions, to what degree is it considered acceptable for mods to be DME'd and to what degree can or should they be DME'd?
Yes, there was some DME at GC and I will admit that the result was probably a slightly (to each their own taste) more enjoyable fight than the one that was written. However, it does beg the question of what folks are expecting when they play, DM, or manage a con like that.
And ... go.
Which adventure(s) are you referring to? I know some of my players in MINI1-1, CORE1-13, and the ADCO really went "off the beaten path", for lack of a better term.
As a DM, I loved it! A little DME can make the difference between a great game and a good game. I'm guessing we did alright, as more than one table picked up lunch/ dinner for me after the game. ;)
Oh, no, this was definitely all the DM.
And no, it wasn't you, warfteiner.
Greetings...
I can only speak for myself, but I don't treat big conventions (or, to fit more closely to your original question, a first/premiere run of any adventure) as necessarily being any different in terms of my philosophy as a DM. If I read an adventure and I think something is going to be a problem, or if the players/PCs take things in a direction that the author didn't anticipate, I'm just as ready and willing to make changes the first time as I am the 10th time.
That said, I probably do change less the very first time I run any adventure, regardless of venue, because I'm not as familiar with the material. If I know I am going to be running the same adventure 7-8 times over the course of the same convention (as is often the case at Origins and Gen Con) then I will often experiment with different ideas at various tables, and by the end of the convention I've usually gotten a pretty steady pattern down. The last 2-3 (out of 7-8) times I run the adventure I will only be looking at the printed version of the adventure when I need to check the stat blocks.
A lot depends on the adventure, too. Picking examples from Gen Con that I happen to be quite familiar with because I edited them, CORE1-13 has a ton of ways for the PCs to approach the adventure and overall it's more free-form than many adventures, so I'd expect to see a higher-than-usual amount of DME going on in that one no matter what. ADCP1-1, on the other hand, is more structured and moves the PCs through the challenges in a fairly straightforward fashion, although they do get to make some choices that can move the encounters around. But I'd expect to see less DME in ADCP1-1 than in CORE1-13. But I wouldn't expect that because they both premiered at Gen Con; I'd expect it just because that's how those two adventures happen to play out.
Not sure if any of that actually answers your question or not. 
Talk to you later --
Sean
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M. Sean Molley | sean [at] basementsoftware [dot] com
LFR Global Admin, Western Hemisphere - South