I tried it out on another laptop since I posted this, and that had the inverse - download speeds went up by about 20% or so, but the upload speed seems have taken a hit of about 10%. On my ‘main’ laptop both improved quite drastically.
So yeah definitely a ‘your mileage may vary’ type of situation, but it’s easy enough to reverse I guess so worth a shot if anyone has a bit of a speed problem. You might get lucky!