My feedback is that I like the update.
For the troop selection, I too would prefer a setting where you could just train the troop you want, without having to opt not to use your sample units.
I understand why the devs have introduced this. Many commanders, particularly at higher levels, have hundreds of sample units in their inventory that they are just not using. However, there are reasons for this.
Firstly, if it's a useful item, like jet samples, they are almost always being saved for Wars where a quick turn around can make a huge difference in a competitive War.
Secondly, for the occasionally useful item, they might also be kept for those occasions when they are useful (eg hunter rancors).
Thirdly, and this is unfortunately the largest category, the units are just not useful in the game any more (eg Dowutin, AT-TE, skiffs, heavies, etc). These units have no place in the modern game. The principal attacking units for both sides in PvP are jets / jumps and have been for some time.
I suspect the lag on these screens, is the game checking to see what samples you have, as you tap in, and then updating the inventory total when you tap out. Seeing as very few people will be using their sample units for the reasons given, this ends up being unnecessary delay, and a cause for irritation.
But the Devs must do what you they think is right, of course.
HQ 10 - Sons of Death
You must do what you think is right, of course.