Hi Matthew,
A few years ago I was researching LMS systems for my former employer a UK Public Sector Organisation and came accross Kallidus LMS. The product fully met our needs, to the point that i became an expert and is now employed by Kallidus supporting the use of the LMS. Check it out it may meet your needs: http://kallidus.com/ .
A full feature list can be found here: http://kallidus.com/Documents/Features%20Lists/Kallidus%209.pdf
http://kallidus.com/Documents/Brochures/Kallidus%20Learning%20Management.pdf
-Can host thousands of users
Yes Kallidus can have unlimitted number of users. Nissan Europe is a Kallidus client with approximately 100 thousand users accross Europe. Specsavers is another client with a similar amount of users accross Europe and Australia. The LMS supports Time Zones.
-Can group like users (companies, job titles, etc)
Yes you can put users into groups and can have as many groups as you like? Users can belong to more than one group depending on needs. You can also create domains with specific administrators for just these domains or groups.
-Can use SCORM (we use articulate to build a good portion of our courses)
Yes most of the Kallidus clients use Articulate Studio 9 & Storyline Content onthe LMS. It tracks perfectly with no issues.
-Has quizzes, tests, and other interactive activities
Kallidus does not have a built in authoring tool however it supports content designed in third party rapid tools like Articulate, Lectora, iSpring and Rapidity.
-Is customizable, offers HTML editor for pages/activities
Yes Kallidus has Google Style Customisable HTML Gadgets all managed simply from the front end by any user with the right admin access? No need for complex programming skills or HTML knowledge. Custom themes can be created for each group of users/domain so you have a different look and feel depending on your domain/group. It also supports most main languanges including left to right languages like Hebrew and Arabic.
-Can do batch uploads of users
Yes users can be imported in batch via a spreadsheet or csv file with a few clicks of a button. All this is done from the front -end no need for access to the database.
-Solid administration settings
Yes fully managed admin with very good reporting capabilities.
Reports can be schedulled to recepients in either pdf or excel format depending on preference.