My two pence worth is that it is a bad idea:
I'll add a real world analogy to this;Using it is the crap idea, it gains almost nothing and more often results in dropped connections by remote peers, thus; actually harming your client download and upload, because some peers will block or choke your client as being 'unreliable' because piece requests are not responded to 'in a timely fashion' or are acknowledged but no payload data is exchanged or provided.
Getting your client settings correct is the 'right' way to 'share' machine resources between a bittorrent protocol client and human usage, "pausing" swarm participation is simply applying rather clunky 'fudge factor' to what is already a 'non-problem' if you spend a little time getting your client set up appropriately.
How quickly would you get hacked off if, you were in a telephone conversation and the other person kept putting you 'on hold' every few minutes because they needed to do something else that was completely unrelated to you and your conversation topic?
That is the same kind of thing that 'pausing' an active peer connection effectively does so this is NOT something that should be implemented, furthermore qbittorrent already HAS a means of temporarily reducing the bandwidth usage by switching to the pre-set 'alternative speed limits' when you want to use the machine for other operations. Another resources using 'feature' to continually monitor the keyboard and mouse activity is really not warranted.
