I don't worry about IE8 so much and prompt for upgrade but do use modernizr, respond. BUT I'm confused. You are only talking about backend CMSB admins and not website visitors, correct? For CMSB, I am fine with you developing for the latest browsers only. We aren't talking about visitors with old browsers. Since we are not talking about website visitors and only admins, we can instruct customers to update their browsers to use CMSB during training. I can't imagine a scenario where a company / network admin can't upgrade their browser for their own website CMS access. I thought the old browser problem on a network was because the company network admin won't update the browser simply so people at work can surf better content that is not work related. What does this have to do with CMSB admins or what audience we design for? We can develop a front end for visitors that is compatible with any browser we want, irrelevant of CMSB requirements. Every customer I have that will update their website with CMSB can upgrade their browser. I must not understand the question?
I'd like to see AJAX features for editing data tables instead of having to click modify and going into each record's details on a different screen and saving. I think all the reloading of pages and submitting is what makes CMSB feel old school to me. If you could expand a record right on one page, fetching the details data with ajax only when needed, searches wouldn't slow down. You wouldn't lose your place while editing long lists of records. Currently, even just saving a record bumps me back to the top of the list. I have a db of 3k records and daily, maybe 20 of them simply need to be checked or unchecked. This is quite a task in CMSB.
Nothing new to you I'm sure, but actual inline updating:
http://datatables.net/release-datatables/examples/server_side/editable.html
pop-ups version:
https://editor.datatables.net/release/DataTables/extras/Editor/examples/inlineControls.html
Bootstrap example:
http://vitalets.github.io/x-editable/
My favorite responsive example of what it might look like even though it's not loading details with ajax in this example ("buy now" could be "save"):
http://quanticalabs.com/script/responsive-css3-data-grids/2581249
So just as you do now, whatever you list in ListPage Fields would be the initial data on the grid. The current "Modify" would be "Expand" or "Details" and would fetch data with a preloader. Expanding for details would be faster for the user and so much more efficient than having to scroll around after modifying and find your place again. A save button for each record would allow inline editing of even the initial data without much extra load. (I actually paid for a custom plug to do inline editing but it initially loads everything with drop menus and checkboxes. It's very slow and even crashes the browser.)