Getting both of the left-side prizes on the elevators is absolutely worth it.
Once you have achieved maximum efficiency at this part of the screen with respect to what the fireball is doing, grabbing the prizes will have a high long term positive expectation, no matter how good or bad you are on the springs themselves (since that part of the screen "cancels out").
Or, to put it another way, if you care about points/pace at all - that is, if you're not just going for a barebones kill screen or speed run - it's actually a fairly significant mistake NOT to grab these prizes.
Why?
First, the points are risk-free. It is not possible to die getting these prizes unless you make one of two mistakes. The two mistakes are (1) mis-timing the fireball and (2) jumping incorrectly from the "umbrella platform" back onto the elevator. But it isn't too hard to get these two things nailed down to virtual perfection.
Second, if you should die on a spring, the prizes act as "death insurance." There are many terrible things about dying on springs, but one of the worst is that, unless you get the prizes, they're "zero deaths." If you're gonna die, it will sting a little less knowing that you at least picked up 1,600 points for the death.
So yes, you should get them.
If the left prizes net you just 900 points per level on average over an entire game (starting at L4), that's over 16,000 cumulative points. That's the equivalent of quite a few bottom hammers and/or groupings under Kong.
Consider the risk, planning, and time involved in those bottom hammers/grouping melees, in comparison to the relative (almost patternable) ease of grabbing the prizes. It's not even close.
And if you're going for a million, not getting these is a sin!