Lol, you complained about Beamer being completely useless when it had range 35 and 2.7 speed, because according to you, in your games, it was the worst experimental in the game. Now that it has just 3 more range than Percies and speed 2, it's OP? Maybe you should not complain for more than 6 month about a unit that you only assume is weak, and base your judgement on actual games.
I don't think it's OP now, it's not that easy to micro against Percies and Bricks with only 3 more range, but if you prove me wrong in real games (owning UEF players with it for instance), it will be reverted. Don't forget that Nomads also have no range bot, and that their t3 tank has less range than Percies and Bricks. Beamer is supposed to help counter Percies and Bricks (and it can hardly do it with 35 range).
ACU speed upgrade pumps 320 because ACU produces + 20, so when it upgrades, it displays 300, a lovely number (same reason why rapid repair drains 420, so that when you upgrade, it's actually -400).