Random Agent Spoofer spoofs resolution along with many other fingerprinting vectors (although for pseudonymity, we don’t care about vm-specific fingerprinting, just system-wide fingerprinting).
The obvious advantage of TBB is that you don’t need to manage multiple pseudonyms (something with which you are very familiar ). As you know, user error working with pseudonyms is very dangerous but helped by the fact that Qubes VMs are so inexpensive.
- Virtualizer does its job
- Whonix does its job
- Iceweasel is no more bug-prone than TBB
- Add-ons do their job
Managing a (manageable set of) pseudonyms should be a viable alternative to relying on a very thin anonymity set. But you should have the last word on that…
Add: Biggest danger is that a fingerprinting vector exists that you are not aware of. If you duplicate the setup across multiple pseudonyms, you could be linked by this unknown vector.