" I'd be interested in your thoughts on Win 8 though. We've just gone through a long period of "gotta have an iPad because...." followed by "how come it can't access office documents, my windows shared folders.....". We're hoping a Windows tablet might solve those problems while preserving some of the iPad's mobility."
I upgraded to Windows 8 on my laptop about a month ago. The upgrade on the existing Windows 7 system was fairly quick and with a bit of study of the users guides available online, in very short order I found the Window 8 system effective and usable. As expected there would be some growing pains and some frustration as you looked for things that it previously been readily to hand.
As a longtime toy lover rapidly approaching Christmas it was only a short leap to begin justifying the purchase of a new computer. The old one had been top-end in 2006 when I bought it and I was still very adequate, but what has need ever had to do with buying a new toy?
I've got a 23 inch touchscreen Dell all-in-one with 8 GB of RAM, a 1 TB drive, and wireless everything. I can see portions of my desk and my bookcase that had not been visible to sunlight for a decade. The migration was far from painless, and I wrote an item about that last week. Now that I've got my essential tools in place and have worked with the new system for three or four days I find it very useful and effective.
Now to address your problem. I love my iPad, but I find it less than effective for doing actual work. It is a media consumption device first rather than a productivity tool. The question of accessing Office documents and window shared folders is not insurmountable. You can use the Apple iCloud, Dropbox, or Microsoft Sky Drive or other cloud storage devices. There are numerous apps that allow you to access office documents in the iOS.
All of that being said, if my concern is actual productivity, and portability is a necessity, than an ultra-book or similar with touchscreen running Windows 8 and Microsoft Office would be your best solution. I'm really not sold on the tablet as an effective workplace tool. The difference in size and weight for an ultra-book with an attached real keyboard and the space necessary for RAM and storage is negligible and makes the investment more justified.
The size difference between a 10 inch screen iPad and a 13 inch screen ultra-book is negligible when it comes to the question of workplace efficiency. Windows 8 is going to build an application store in the next few months that may lag behind Apple's library, but will provide everything of significance that you might need for your Windows 8 system and in short order you will never miss your iPad.
Will there be growing pads and gripes? Certainly, but we saw that when Windows 95 came out, with Vista, and who will ever forget Windows ME?
The bottom line question as always as what's the dollar value of your capital investment fund?