Please pick this dice mechanic apart

I've had this dice mechanic cooking for a while and wanted to see how it sits with other dice enthusiasts. It's nothing super revolutionary bear in mind, I just tried to cram all the things I wanted, to it.

Things I wanted are:
Dice pool - I love the feeling of more dice equals more power.
Only D6 - It's not a must, I like them and kinda wanted to challenge myself.
Scalable - It will be used with a medium complexity RPG.
Quick to read - Multiple actions will be made in a turn.
Only one roll - Again, to make the game go faster.
Have a critical component - I wanted all the characters to have same-ish critical chance, which is hard with typical dice pool.

The Roll (at this point)

Check your skill number and gather that many dice in your pool. Your skill is written in two numbers, lets say 3+2, or 5+0, or 1+1. The first number is regular dice and the second is more valuable critical dice (I wanted to have just one type of die, it just couldn't accomplish what I wanted with critical strikes and scalability).
Roll the dice, read only the highest number and its duplicates. Each duplicate gives +1. Compare that to the given target number.
For example a roll of 2, 4, 6, 6 equals to 7, a roll of 5, 5, 5, 5, 6 equals to 6, and a roll of 4, 5, 5, 5, 5 equals to 8.
If any critical dice are read, it is a critical hit, and how many crit dice are read the better the effect.

(Note: D6 has pretty big chance of doing a critical strike compared to the D20, this is why my crit effects will be less powerful than the ones in that popular D20 RPG game, but you can get multiple ones in a single strike, so it's a bit more granular).

Why the pool with two different dice?

Dice pool is a must for me, not negotiable.
I'm thinking of keeping the maximum dice limit at 10, but that will reduce my scalability. That's why I have the crit dice in there - when you are leveling your dudes, you'll hit that normal dice cap relatively soon if you don't invest your exp in the better crit dice.
Those crit dice will also go along with character diversity. Those who invest heavily in critically nuanced weapons need to go for more crit dice, and those who just need to have their things done consistently don't need them that much. So you can build your dudes up with the combination of dice you think has the best bang for the buck.
One convoluted example would be a mage, that mage is spent and has nothing to cast anymore. He also has a cheap crossbow, but with a powerful critical effect. He doesn't need a powerful crossbow since its not his main style to deal damage, so instead he went with the good critical effect. This character would actually want only critical dice for his crossbow skill when he has the exp to spare.

Why read only the highest?

To be honest I might still go back to the regular dice pool of counting all the ones that hit the static target number... But what I did here, I put these two systems against each other and started rolling, and timing. The read highest only was almost 20% faster to come to the conclusion.
I also liked how it allows more fighting chance for those who have less dice.
What I don't know yet is how I feel about the curve at the higher end.

Is it simple?

I try to keep it as such. GM calls the check and target number, player looks at the skill which says X+Y, he then rolls those dice and checks if it got over. A one single modifier might get thrown in (just add it to the number rolled), but nothing that would require any math before or after making the roll.
I keep decision making out of the roll too, no extra resources that can be used to affect the roll, or even re-rolls. Players make their choices after and before it.
In my experience that is one of the biggest time chunks when making the rolls, players pondering what items and stuff they should use when rolling.