The greatest pain that I can see is the prerequisite "Points Spent In Tree."
The problem is, when you move over to a new tree, you have to spend the same minimums to climb up the tree. We only have 80 points to spend which forces one to either specialize in one tree or just take the basic minimums in two or three (keeping in mind you still need to meet feat prerequisites as well still).
I would suggest making the "Points Spent In Tree" prerequisite for each enhancement be global across trees so that you don't have to always start from the bottom. If you have the "Points Spent" minimum established in say Arcane Archer, you should be able to get a higher up enhancement from another tree so long as you have the feat and enchancement prerequisites (not the "Points Spent In Tree" for that specific tree). This is the mechanic that will restrict multiclassing in my opinion. One already is forced to take lower level enhancements they may not want in order to move up. Repeat that on the next tree and more wasted points. Then on the third tree and...you can see how it gets expensive real quick. And this is regardless of the build. This goes for really any multiclassed character.
No Sprint Boost enhancement (must have feats for Tempest to get that from that tree).
All the new Arrow Attacks that require spell points and have a cooldown.
There is a reason Deepwood Sniper never took off before and (at least for me) the main reason was because I had to remember to click something every 20 seconds or so. Now that mechanic has been expanded to Slaying Arrows -- the main draw of Arcane Archer for the last few years. So now Slayer Arrows require spell points (20 points per click) and can only be used once every 20 seconds. Don't know about others, but if this goes in as is, I'll pass on it.
Secondary stances in addition to primary stance (multiple imbues in effect).
Metalline arrow stance.
Bludgeon, Slashing damage stance.
Elemental arrows with other effects when you get Improved Elemental Arrows.
For me at least, bottom line for Arcane Archer are more imbues and or stances (even possibly tertiary stances in addition to the secondary) and fewer things you have to click to proc -- especially when that involves spell points and cooldowns. Most AA's do not have a whole lot of spell points to work with and it gets even less when you are talking about pure Fighter AA's for example. Even if you get rid of the spell point usage and reduce cooldowns, I personally just can't be bothered to remember to click various Arrow attacks along with all the other hotbarred buttons I already have tied to my number keypad.