Not quite back to back but we switched from a well sorted Pro Systems 1050 on an Indy 440-3X to an Indy T/R with 2 x 1150 Gen 3 Dominators, from one season to the next.
This is on a 580 engine (4.53 x 4.5). Best to best the difference is only 0.06 in favour of the T/R. However the single only ever ran in the 9.50's once (9.57 @ 142.7) and was used for 8 seasons, the T/R has dozens of 9.50 passes (9.51@142.5 best) and has been on from 2017. Best MPH has always been around 142 with both but the T/R has carded a lot more in that region.
The other caveat is the car had an extra 100lb + added a season or so before the T/R was fitted, Then, the 1 x 4 was normally running around the bottom 9.7's with a best of 9.6 something.
The car is 4023lb w/d last time we weighed it. Wallace would calculate the 1 x 4 at around 880 hp and the 2 x 4 920 hp, again best to best. Unfortunately I can't back it up as the 580 motor has never been dyno'd.
I'm pretty sure the T/R carbs are too big for the engine and it may run quicker with smaller carbs but after a season of tweaking they run well, they were originally specified for a 655 which we "borrowed" them from so they won't be changed.
On this engine I would have likely done the swap even if I didn't have the T/R and carbs already but with 1050's. I do like the look of a T/R but the cost of swapping would now be $3500+, though you might get back $1500 for the single stuff. So is the "maybe" 40 hp worth $2K ? Not the best hp per $ return I know but we did pick up something

HTH's