Best abstraction to run simultaneous workloads on multiple browsers ?

[Niels van Klaveren]

Say I have several scenario's of serial transactions (consisting of several operations) on a browser through clj-webdriver, that I would want to run in simultaneously on multiple browsers.
Each action should log some results (timing), preferably to a shared data structure for all browsers (either an agent or an atom).
If an action fails (exception/timeout), the browser should be reverted to its original state (by logging in to the original site again), and start the next transaction.

What would be the best abstraction to do this ? I've tried / contemplated futures, browsers as agents, pmap or even reducers.
All seem to have their different pros and cons, and frankly, I'm only getting more confused.

Agents seem to have a nice fit with reset functions and a task queue being implemented, but as far as I can tell, there's no way to put each action queue on one thread for one agent.
I read something about a new send-via option for agents in Clojure 1.5 which might be relevant, but documentation and examples are almost non-existant.
Future's supposedly can't be chained, so if futures would be used they should contain a map over the whole scenario for each browser.
Exception handling and resetting should be handled by my own code within this map loop, as well as transaction support.

What would be the best abstraction to do this ?