Some great points here and in your prior post, Tom. Since I don't live in the area, I appreciate your perspective. No doubt the construction, either way, will be expensive and could run over budget and/or time. Those factors are there regardless of which option the U chooses. I'm still wondering if the Drumlins option involves a new building, or is that a parking option? Is Drumlins University-owned? (It's close to South Campus and I-81, correct?).
At any rate, the BC Place example (which seats +/- 55k) is an interesting parallel. It has about the same capacity as SU's facility, and it involves the renovation of an existing Dome'd arena. However, it's also a crown facility in a Canadian province built for public use. From your list, it appears that the Crown spared no expense ... including a highly complex retractable roof with all the cabling, mechanicals and structural support needed to get this done.
If we're to learn a lesson from BC place, it might be this: Public dome'd stadium renovations involving retractable roofs are complicated and expensive, especially when (Canadian) taxpayers are footing the bill.
Here in upstate NY, the "re-do" proponents are talking about a much more scaled down project for private/semi-public use. For example, I don't think the U is giving serious consideration to a retractable roof. That would, as you point out, be very expensive and complicated, and would probably outstrip any State funding assistance we could obtain for a private facility ... even if public events were occasionally held there (as is the case with the Dome).
However, if the roof is fixed, as I understand the latest proposal, the complexity, structural improvements and construction time would be substantially less. That doesn't mean it won't take 2 years, or that it won't be hell for a while. But unless SU is prepared to bulldoze the Dome, a renovation is going to be necessary. We don't know enough about the cost figures to compare the two options at this point. But one thing I know is, something has to be done with the Dome either way ... and if it's to be preserved and used, it's going to be expensive. If that assumption is correct, the "new stadium" proponents are actually suggesting that we do both ... renovate the Dome to keep it relevant AND build a new public facility through NYS that caters to regional interests.