Just got the email this morning.
35% off sale

Mike

You can install the Vegas 13 trial on the same machine, and even open both at the same time to compare.

There aren't any major new features for most people:
http://www.sonycreativesoftware.com/vegaspro/whatsnew

I used to upgrade routinely, but for many years now Vegas has been buggy for me. Each year comes, and it feels like they tack on some new code mostly only so they can increment the version and get upgrade money from the others in the upgrade habit.

But I think there was community backlash, and less people upgrading like me, so they seemed to slow down on the annual release, and version 13 was released late.

2007-09 ::: v8
2009-05 ::: v9
2010-10 ::: v10
2011-09 ::: v11
2012-11 ::: v12
2014-04 ::: v13

They repackaged Vegas Pro in new editions, Edit, and Suite.

For a 4K display, I went into the properties for the Vegas Pro 12 shortcut and set "Disable display scaling on high DPI settings", and the graphical interface looks nearly identical to Vegas Pro 13. The icons are tiny, and the ones in the Explorer look larger but fuzzy.

On my machine, using Windows 10 and a Quadro M4000, the Vegas Pro 12 video preview shows higher framerate than 13, and 13 uses less GPU according to Nvidia's resource monitor. I tried to keep the settings the same on both, but maybe I missed something.

I would test the trial against version 12, because for me the decreased performance meant I would not be paying for an upgrade.

Version 12 crashes for me frequently, so I save the project often. I didn't spend enough time in 13 to compare, but it felt like it might be a little more stable.

Overall, at least in my case, both applications appear identical, and even if the performance were the same, there isn't any apparent difference to justify spending more money. If there's a specific change you need, like support for your camera format, then you need to upgrade. Otherwise, you can probably safely skip it.

I think the legacy codebase of Sony Vegas Pro has become a perceived hindrance to the developers. Part of the justification for paying to upgrade previous buggy versions was to support the development effort, with faith that they'd pull through and fix everything. But the evidence suggests that Vegas Pro has long since matured, and there is less potential for progress to be made.

It appears maybe the focus has shifted to other projects. If Vegas Pro is to continue, I wouldn't be surprised if there's been talk to rewrite and reassemble most of it, to be something more modern they want to continue working on, with cross-platform support.

The Catalyst Production Suite is what has the spotlight now.

Maybe they faced a similar legacy situation with their RAW viewer, and Catalyst Browse and Prepare was their modern rewrite of that:
http://www.sonycreativesoftware.com/rawviewer

Then maybe Catalyst Edit is their start towards a modern Vegas replacement.

The new upgrade of Edit was released a couple weeks ago, with major feature upgrades, showing that the gains in development are now in that product, not Vegas.

http://www.sonycreativesoftware.com/catalystedit

It is still missing a lot, especially on the audio side, as Vegas originally was a multitrack audio editor, and Edit is video first. But if I were to purchase software during a sale, I would get the Catalyst Production Suite instead of Vegas Pro 13. It's more likely the upgrades for that product will be more valuable than Vegas, and already as it is there are some aspects of Edit that are better than Vegas.

Not seeing any sale prices...

It's through an email link. Here are the full and upgrade prices, until November 30th:

Vegas Pro 13 Edit
$260 / $130

Vegas Pro 13
$390 / $163

Vegas Pro 13 Suite
$520 / $293

Jamon, thank you so much for all of that info, I really appreciate it. I haven't been following this forum and am unfamiliar with Catalyst; I'll check it out. The other appeal of the suite upgrade is the latest Sound Forge, DVD Architect, and other program upgrades being included as well as Vegas. We'll see. Thanks again.

Does anyone know if Sony allows an upgrade price from Vegas Movie Studio HD Platinum V11 (old version), or is the upgrade pricing only within the Vegas Pro line of software?

It does. Read here.
Look out for special offers though.

I'm clicking the links, but it not showing sale prices. Upgrade from Pro to 13 Pro Edit is $199.

It is still missing a lot, especially on the audio side, as Vegas originally was a multitrack audio editor, and Edit is video first. But if I were to purchase software during a sale, I would get the Catalyst Production Suite instead of Vegas Pro 13

though cat edit appears to be where scs is heading, it's VERY, VERY far removed in terms of functionality compared to vegas. it has great potential, but whether that is ever realized will be something we'll have to wait and see. meanwhile, unless your acquisition requires it, or your workflow is relatively simplistic, edit would suffice, but not come close to what we have in vegas...