@Stephen-Schaff thanks again for all the thoughts. This is making a lot of sense.
To summarize the Multistage-approach, "each build is done in its own sandbox so that the tools used to build the software are kept in lock-step with the software", or something like that.
Anyways, I really dig it, and I like where your thoughts are on this! This is the sort of "engineering/process rigor" I always envisioned to help companies build with our tools.
Actually, I'm already thinking of how we can do all of this with not just ProGet (probably using a function I spec'd out ages ago... happy to share that idea with you at some point, it'd totally work I think), but also integrate some great self-service workflows into BuildMaster for this sort of thing.
Now all that said.... I'm an engineer by trade and by training, and maybe ten years ago I would jump on this idea, and code it all myself over a weekend 
My company starts to balk after you get over a few thousand dollars unless the value is really big.
As well they should! I do the same 
The reason I ask the "how much more would you pay" question is to get a "gut feeling" for demonstrating/articulating value. It sounds like this gap is pretty big right now, and that's something I'd like to work on.
This is more a marketing exercise, and not something I'd normally do in a venue like this, but the next InedoCon is a ways off, and you seem to have a great grasp on these topics already!
Now just to be clear, we don't intend on price hikes, especially for a feature like this, but one of our biggest challenges (thanks to an engineering CEO
) is demonstrating value to buyers.
So working on this, some quick back-of-the-napkin math shows that "30% of $2k/year" is $600, or at most 6 developer hours of internal value (whether that means saved or gained). That's not very valuable.
What I'd like to demonstrate is the business case for why this feature is easily worth $10,000/year (and probably even $100k/year) to companies with 50-100+ developers. That would be very valuable.
This is a really difficult exercise...
It's actually pretty easy easy to do demonstrate this kind of value with the high-availability feature alone. When 100 developers lose an hour of productivity due to a failure of ProGet, that's $10,000 lost. If your ProGet Basic instance goes caput, you'll lose a LOT more than that.
Of course, the problem with the high-availability feature, however, is the skills and mindset required to monitor/maintain high-availability things. If you don't have the infrastructure team on call that knows how to monitor, how to respond, how to support developers, etc., then it's not a feature you can use.
The value of this feature idea isn't so clear, at least in terms of Time (delivering quicker, increasing productivity), Money (lowering labor costs, increasing profits), or Risk reduction.
But even if we figure those out, the major problem I see with this feature is the skill/complexity in using it.
With the high-availability feature, you need to have a high-availability organization, but a lot of organizations already have that, so it fits right in.
The knowledge/skills gaps seem much larger, and the Problems an organization would need to have are complex. A buyer might think, "So an 'unapproved container' made its way to production, despite passing all the acceptance tests... is it really a problem?"
Anyways just brainstorming! But this is just part of the process.