Apologies for the tardy response... The flu got me.
So the fact that you're looking at this from a business perspective changes everything. Your evaluation process should be much more detailed and exhaustive than someone looking for personal use like myself. It was ridiculously easy to dismis TM as a choice based on price alone. You cannot afford the same luxury. You have clearly already surpassed my own research, so that's good. From a business perspective, any difference in accuracy is too negligible to matter, so let's move away from that. Great point about Breed and Hall using FS, but don't think for a minute that it's not marketing driven as well. That doesn't devalue the point though. Marketing is of course a huge factor for you, to you very last point. Selling your business with TM will be easier than with FS. TM provides better legitimacy factor due to public perception. Not only a result of TM's marketing, but public and professional reputation as well.
I couldn't agree more that TMs outdoor functionality is grossly overpriced. Probably helps pay for better R&D and of course, better marketing. That better marketing is a favorable attribute for you, though not really for me. Being a business decision you'll need to go beyond simple research. I don't think you have a choice but to call TM and have them come out and do a demo, if you haven't already. You also need to keep in touch with FS and have them continue to sell you on why you should stick with them and inform you about what new features and functions are on the horizon. You have to allocate the time to vendor management, and they should be considered as such. The other thing you have to do is talk, write and visit peers that are using each... Go see multiple setups in person and get firsthand feedback. This is probably all stuff you already thought of, but I throw out to you just in case. Being in the business of business, I know the importance of these things to maximize growth. Good luck with what should be a continual evaluation.