I'm in a similar boat except that I think I can keep the good (C# / .Net) and leave the bad (Microsoft Analysis Server). We are looking at scaled DB backend us

I'm in a similar boat except that I think I can keep the good (C# / .Net) and leave the bad (Microsoft Analysis Server). We are looking at scaled DB backend using column stores, multiple compute instances feed through message queues running on Amazon or private cloud, and a mostly Javascript / HTML5 front-end. It is all tied together with C# and so far it doesn't look like it will be too bad. Not surprisingly, the stickiest part of the puzzle is... Microsoft Excel, specifically Pivot Tables. Weird but true.