Hello, resident Yi main. Have been a Yi main for approximately 3 years.
"Crit focused"
Okay, so the first thing here is that I have to disagree with this. The primary build at the moment (and almost all the time) is attack speed, and you're focused around delivering many swift strikes rather than bursting down a target really quickly. Additionally, you're effectively planning to gut out Yi's many build paths, which are, in my opinion, something nice about him. He has a crit build, a bruiser build, a tank build, a flat AD build, and an on-hit build, and there's many builds which are somewhere in-between, and generally they are all viable.
My gripe with your Q is that it slows down Master Yi, even though he's supposed to be this wicked fast "you can't see me" swordsman. You're also effectively gutting the thematic space surrounding Alpha Strike. I see this often-- turning Alpha strike into a dash-- an I honestly hate it.
Secondly-- if the speed of the dash is approximately the same as Kai'Sa's R, is there REALLY a skill requirement? It's still effectively instant, and can no longer be used to dodge abilities like the current Alpha Strike does (which is how you differentiate a good Yi from a bad Yi).
Thirdly, this ability just blows Yi's mobility out of proportion, and gives him one of his weaknesses: a reliable escape.
"In short this ability to Yi's current Q but actually takes skill." Apologies, but this is just flat-out wrong. Assuming you're untargetable during the dash, which, might I remind you, is going to be a fraction of a second of untargetability due to the speed at which you travel, you're making it only a gap closer with incidental ability to dodge abilities, whereas the current Alpha Strike actually encourages people to use it to dodge abilities, such as the crowd control that utterly destroys him, and, again, separates a good Yi from a bad Yi.
You're also doing the same thing to Meditate.
Thematically speaking, when you meditate, you SIT STILL. I'm also not sure why the shield exists.
I'm not sure if you know this, but Meditate is commonly used as a way to soak up damage. Yi's entire kit is built around the concept of mitigating damage and punishing enemies for not being careful with their spells. Turning the damage mitigation into an out-of-combat heal, followed by a shield and increased out-of-combat movement speed, does further to push his mobility to ludicrous amounts and gut the thematic idea behind a meditation ability, as well as push him away from the idea of mitigating damage.
A little-known fact is that Meditate can also be used as an auto attack reset, which is, again, one of the ways you separate a good Yi from a bad Yi. I often find myself using it as both a mini-spell-shield to block something important (Veigar R) and cancel an auto attack at once with good timing. This change would, again, lower his skill requirements, which is the opposite goal.
"Master Yi's movements becomes dashes for a duration or until he uses up all his dashes."
I... don't see the point in this. This will just make him even more infuriating to deal with, since now he's, again, running around everywhere and harder to keep track of. You're also making it easier for him to dodge abilities, which is, again, the opposite goal here: we want to make it harder for him to do so.
This would also just feel clunky to play, since when you try and stick on a target without using a charge, you HAVE to use a charge, instead of just hitting R again to use a dash.
You're also pushing his thematic into a weird place. Forcing him to stop between strikes is just weird. I understand Meditate may seem weird, but it seamlessly flows into his kit as it is now due to the prior-mentioned mechanics, as well as being "okay hold on a minute before I go ham again," rather than "START stop START stop START stop START stop."
