In the current state, this research is close to useless for anything except optimizing delays on rare delivery events or keeping up with the players movement speed (up to hard limits, too). It doesn't work at all for increasing throughput in stationary factories. With the research cost increasing at a potency of 2, it's by far too expensive for a technology which has already hit diminishing returns prior to endless research stage.
The main issue is that it's significantly decreasing the time between recharging at roboports, but the recharge time itself remains a constant. As a result, robots zip faster from Roboport to Roboport, but then just pile up there, waiting for their turn to be charged. Eventually you can no longer scale up the number of Roboports (worker robots are not exactly smart about which Roboport they pick for recharging), so you inevitably hit a hard throughput limit.
As it's mentioned on the wiki ( https://wiki.factorio.com/Worker_robot_ ... rsus_range ), the current formula for consumption also doubles as a constraint on the distance a robot can move without recharge.
Now, there would be three possible approaches:
- Scale the recharge speed with movement speed. Late game, when you can afford that research, both your modular armor and your energy grid should have sufficient spare power left to afford a proportionally increase in power drain from Roboports. Given a constant number of worker robots, and a constant number of Roboports, this would then just result in a net throughput gain without otherwise impacting distance constraints or worker robot energy efficiency per unit traveled * item transported.
- Scale per-tile movement cost inverse proportionally with the speed bonus. Keeps the pacing for the recharge animation unchanged, but has several implications. Foremost, maximum distance for worker robots effectively increases, and so does the downtime for approaching a recharge station. Also effectively reduces energy cost per distance traveled.
- Increase recharge rate as per 1st approach, but additionally also increase the internal capacity of worker robots. Maintains constant efficiency, but has otherwise all the benefits of the 2nd approach.
The 2nd approach provides excessive benefits, by both netting an efficiency increase as well as increased performance simultaneously.
The 3rd approach IMHO provides the best user experience.
The scaled up maximum distance is a welcome improvement for late game. Especially also considering the tendency of robots in networks with concave shapes not to follow the logistic links, but rather to take "shortcuts", so that plays well together.
By reducing the effective frequency at which robots need to recharge, it effectively combats congestion around the charging process.
Scaling the energy consumption per Roboport is in line with other late game mechanics (tier 3 modules etc.).