@R_Colin_Johnson "Forgot my gesture" is a great new feature to implement. I must admit that I've been encountering a much more mundane issue. When I visit web sites after a long time, they've forgotten my login and password even though I went to the trouble to remember it myself. When I raise the issue with customer support, they say: "We changed computer systems so all the old data was lost." Seriously, I can't count how many times I've been told that. The double standard is outrageous.
I just upgraded to an iPhone 5s (because Sprint is giving them away free--with no contract and they pay the $27/month you would usually have to pay to slowly purchase the phone). The only catch is that you have to stay with Sprint ($50 month for unlimited text, voice and 1Gbyte of data that I've never gone over).
But back to your excellent point of upgradability. I backed up my old 4s to the cloud them restored in on the 5s and had all my settings back without a glitch. That's the kind of service you would need for these user defined gestures (also a "Forgot your Gesture" feature like the "forget your password" today).
Many of us personalize our computer interface to make our devices more usable - and this gesture technology sounds like it could significantly extend that personalization. There is, however, a dark side. If your computer or phone is lost or destroyed, your replacement device will run with the commands that you've long forgotten. I'd guess that it takes most power users a long time before a replacement device is fully functional and reconfigured. [Even when the old computer is at hand for a migration with data transfer tools, I find that for weeks afterwards there are odds and ends that are not right and must be addressed. Inevitably there has also been an operating system upgrade in the interim so it isn't possible simply to mirror the setting on the original device on the new one.] Cloud computing may help if the original device is lost (APPS and data can be downloaded to the new device) but the process remains a nightmare for most users.