Task switching in iOS is pretty horrible, as with most mobile OSes. If you're switching behind that many apps you must have a high tolerance for pain.
Also I disagree with you that iOS is good for professionals. The way it attempts to hide the idea of files makes it very inconvenient to work with (coupled with the lack of a compelling alternative). I can't think of any professions where files aren't important.
"The way [iOS] attempts to hide the idea of files makes it very inconvenient to work with"
It doesn't hide documents, iOS has a different way of presenting and organizing them than you're used to. Instead of putting them all on one pile for you to sort out, iOS takes an app centric approach. You never have to search for that spreadsheet you made last week, you know it's in the file drawer in the Numbers app (and with iCloud, the spreadsheets you made on your Mac will also be there).
Of course the standard way iOS handles files doesn't work for everyone. If you have thousands of files you need to sift through, you might prefer using Dropbox or SFTP with an app like GoodReader, or use a web app like Google Docs.
The app-centric approach breaks down when you have to share that data out to colleagues who collaborate on it or gasp use it on a non-Apple device. These things can be fixed but as it stands you really have to go out of your way and adapt your own workflow because of the limitations of the platform.
I found that task switching in webOS was REALLY nice.. and am glad that Android has since adopted a similar switcher. Now the lack of a physical menu button on most android devices is a different issue.
Task switching in Windows 8 is also really nice (very similar to Web OS). Swipe in from the side to show the task switcher, then click on what you want. Snap a second app to the side of the screen if you want. Very nice balance between keeping the interface simple and offering some flexibility.
Also I disagree with you that iOS is good for professionals. The way it attempts to hide the idea of files makes it very inconvenient to work with (coupled with the lack of a compelling alternative). I can't think of any professions where files aren't important.