I got off the treadmill, stretched for a few minutes, then went to the locker room and took my blood pressure-- it was 120/85. 10-15 minutes later, after I got home, it was 109/70. I'm quite happy with those numbers. (For those who don't know, blood pressure normally rises during and immediately after exercise.) I have no idea how long it takes the effects of Benicar to completely wear off, though, so I could still be partially "under the influence".
My plan is to park myself at W5D1 for a few runs before trying to move on, so that I have a steady base from which to monitor changes in my blood pressure and how I feel after a run.
I don't know how much of the improvement is due to no longer taking Benicar, and how much is due to it being an easier workout. Whatever it is, I'm glad not to feel like I'm going to keel over when I get off the treadmill. I'm really glad I called bullshit when I did, rather than trying to push myself through more of the feeling crappy stuff.