Of course, it would be a rapid climb... That was my point, an aircraft that suddenly loses 25,000 pounds of ballast would rise rapidly and correspondingly lose lift (which could cause it to stall and "fall out of the sky.")
Further the challenges of keeping such a bird aloft in a canyon, filled with wildfire smoke and in the midst of swirling and dangerous winds can be quite significant. What actually happens to both fixed wing and helitankers is an immediate need to drop the nose and INCREASE THE POWER to maintain control and keep the helitanker in the air. Followed by an immediate need (in most cases) to immediately climb to avoid smashing into the mountain ridge dead in front of them.
And this flight action is further complicated by the need to hit the flames they are aiming at. Quite often I have seen pilots drop the nose drastically seconds before a payload release so that they can aim the drop at specific flareups as the helitanker pulls out of the dive.