(I sure am late responding to these two issues... sorry Scott!)
I considered this sort of functionality when I was initially building the software. It seemed like a whole lot more work, and I decided to go the easy route first.
Now that it's been running for about a year, it makes it far easier to judge how useful a new feature would be. Only 19 people out of 52 even bother to use the "descriptions" feature of the collection manager and fewer still (12) are using the "quantity" feature. I don't know how many of those have bothered to enter custom descriptions rather than just go with the default. I suspect it is under a half dozen.
Your second point about providing a way to download the collections is an excellent one, and is something that should have occured to me a long time ago. What do you think would be a good export method?
- "report" style that shows up in the browser and you print it out or save it locally
- "spreadsheet" style that gives you a file to download that you can import into Excel, Access or whatever
I built a site a few months ago (http://MuscleDB.com
... isn't it sick that I built that whole site just to gather a collection of that stupid Rubik figure?), that has the above mentioned "spreadsheet" feature. Furthermore, it allows you to IMPORT a spreadsheet if you want. People export their sheet, make a bunch of changes, then can import it overtop of their current collection. Perhaps this will help satisfy the desire for the mass-modify feature you were talking about before.
Let me know what you (and anyone else too, please!) think about all this.