This is where I will post my personal Suggestions and Ideas. Here's a few one!

Feature Idea
1- Make it so the Skill System is openable through the Hud. In that section where you can make Blue Prints or Copy Paste. The Button is there but it does nothing.
2- Add a togglable XP Bar Hud Element at the very top of the screen, just a small thin line.

Rebalance Idea
1- As it stands right now, the bonus that allows inserters to pick up more items turns the Fast inserters into Bulk Inserters as they end up being able to pick up exactly the same amount of items and it interferes with builds when you don't want Items to be picked up in Bulk like the Bulk Inserters. I think it also does that with the regular Electric Inserters.

1) I am a key bind person so rarely use on screen elements, but I will look into this, I can't remember seeing the button, but I will get that working.
2) I like this idea, I wouldn't want to add too much to screen cluter, but a visable xp bar seems reasonable.

Rebalance
This is a fair point and I have noticed it myself with higher throughput. I like the increase item pick up, but it does need to be scaled better for fast inserters and keep a clear upgrade path. I believe bulk inserters are still faster

I have been doing a tonne of background changes to get the mod ready to be more accepting for how I see it in 2.0 so feed back like this really helps me move forward as to what the player may want moving forward. Your suggestions are added to the list, I expect within the week I will have something to show for it.

Edit:

I'm daft, Re read your rebalance idea, I get you now, I whilst skills can be toggled, I think removing fast inserters from the entities it's affected by may be the answer here so they will always act as expected, whilst bulk inserters should just get better at bulk.