I did some back of the napkin math, and with that extra pack it would provide 10% mroe capacity, but likley not provide extra 10% flight time. Let me explain:
The 1hr pack uses 11P 4200ma cells, total of 46200 mah in the pack.
This pack is “quoted” as 5000mah. So you could essentially treat it like a total 51200 mah pack when added to the 1hr battery
So theoretically with the extra pack you have 1.108, or 10.8% more battery capacity.
Or 6 minutes considering the 1hr flight time standard claim.
The challenge will be matching the current draw of this pack and the main battery, they may or may not scale correctly. The SP140 could easily overload this batter and cause it to shut down.
Beyond that, it weighs 7.5 lb, which is quite a lot, most of it being dead weight like an extra BMS, non optimized case design, and extra USB-c ports and internal voltage regulator.
The additional 7.5 lb will reduce your flight time by a little, I would guess that adding one of these would result in maybe 3-5 minutes extra flight time which just seems not worth it.