You can swap them for a very minor pps loss. It would be a pps GAIN if your ping is causing you to miss the ninth hit of BFB. Using it as HT>BL+BFB>etc should have it last JUST long enough to catch your second 4th hit, but only with 100% uptime on the boss and perfect hitting of the GCD skills. The timing becomes looser with more SS; at 2.40 even it's REALLY tight. If you physically can't make that 9th gcd, it'd likely be a gain for you to swap it. In my opener I use 99.99% of the time (because Potions are expensive and rarely needed) I do:
HT>[BL+B4B]>ID>[IR]>Dis>[BotD]>CT> same as normal
So it's really easy to (if your B4B won't last) just shift the B4B to couple with IR instead without issue. It only becomes a swapping situation with Pots.
