Weapons development is a viable option now since you can choose what you get instead of spending a lot of $ and getting super subs.
Even though it’s six times as easy to get the tech you want, the risk associated with it doesn’t translate well into consistent strategies. If you roll 9 die of tech (45 IPCs) you have an almost 20% chance of NOT achieving the tech. That sounds pretty bad, doesn’t it? Ironically super subs is the only tech that I try for, and only if I’m the US and gunning after Japan. Rockets are pretty good for Germany but I really can’t find space in my economy to throw away 30+ IPCs for an uncertain tech. If you’re a habitual gambler or feel like you’re playing against superior player so you need to take your chances, then I would say tech. Otherwise, it isn’t going to win you a whole lot of games unless you are already winning.
One part of the game that I have not explored is the option of the US going into the pacific in a big way. Of course, the pressure off Germany is a huge reason not to do it, and it was hardly ever done in the old game. But the increased value of the islands make it more attractive.
This is pretty fun to do if you have all the Allies cooperating against Japan. You can really make Japan squirm if the US is dumping all cash into a navy while Russia/UK swipe the Asian territories away. If the US smartly maneuvers the navy and researches super subs right before a big battle, likely Japan is going to be staring at an 8 IPC paycheck and squatting on his capital for the rest of the game. But yeah, taking pressure off Germany is a pretty big no-no. You’re leaving 10 IPCs in Africa alone to Germany (couple more in trans-jordan/persia as well) and letting him hammer Russia with full strength, which is much harder to defend against than a Japanese attempt. I admit I’m not an expert though; I haven’t taken that many games to conclusion in a real bonafide KJF strategy. It’s hard to say if the Allies can recover or not once Germany kills Russia; perhaps taking the Japanese mainland gives the Allies too good of a position to retake, but then again maybe Germany takes too many IPCs and can overrun the UK in short order and then the US.