As a Yi main since season 2, I must say this revised version of Master Yi is more polished than on live. There are however some changes that I'd like to elaborate on especially in regards to his E and the balance direction Riot is taking with Yi. If you'd like to follow along, I've provided a link to the current changes on the PBE I'd like to give feedback on after playing him.
**Alpha Strike (Q)**
Removing Alpha Strike's (Q) cast time has given Yi more consistency in chasing opponents and avoiding damage from abilities due to previously being locked in cast-time. On live servers, using Q leads to situations where casting it on enemies near fog of war causes you to fail in closing the gap if the target moves into fog during cast time. This PBE change will eliminate that clunky interaction if it goes through. Another positive change to Q is the extra damage given to isolated targets. This is a nice buff for players who utilize the ability for heavy AD builds. While the duration change to 0.8 seconds regardless of target numbers is slightly detrimental to Yi's dodging defense against certain CC's (Jax E), it does help him more when isolated when compared to Live's 0.25 second dodge in isolated areas. Definitely a skill check in that regard.
Without the cast time, I do feel like I have better access to meditate for burst negation and auto-attack resets. This does make Yi feel smoother.
In my opinion, I would consider this to be a net buff to Master Yi. Converting R's movement speed (MS) from multiplicative to bonus means MS boosts from other champs (ex. Karma, Zilean, or Lulu) and items (Ghostblade active) won't be as effective. However, the higher MS provided in PBE is more powerful on its own which makes Yi more independent; allowing him faster and more consistent access to targets. Also, the 9/5 split (duration and duration extension respectively) is a great buff to his potential as a duelist while still retaining his ability to clean up teamfights.
**Wuju Style (E)**
I'm not a fan of this change because I feel the direction of it is misguided. While the rest of the changes serve to add modernization, consistency, and some counterplay, I think the problem from Yi's scaling actually stems from his popular On-Hit build. E's passive gives him bonus AD from runes, items and base AD, only one of which the On-Hit build uses most (base AD). As far as items go, the usual item core for On-Hit Yi requires Bloodrazor and Guinsoo's, followed by Wit's End, and sometimes Death's Dance and/or BoRK. The usual build combined with E's 10% passive rewards Yi with +2.34 from runes (slot 2 shard with level 18 conqueror), +12 from his 2 AD items (IF he gets them both or at all), +11.7 at level 18 amounting to a sum of 26.04 at level 18 of lost AD for the On-Hit build. From my experience, the present On-Hit build is made to stack conqueror as fast as possible to convert every item's type of damage (percentile, magic, slight physical) and phantom hit. I think the problem is not the scaling Yi has with AD but the synergy provided by **Guinsoo's and Double Strike** with Wit's End and Bloodrazor. The E change is a big nerf as expected for AD/Crit builds and it's negligible to solving the problem that is the On-Hit build.
In short, RiotRepertoir's changes do a nice job in making Master Yi more fluid to play and fairer to play against. However, they miss the mark in addressing Yi's low AD, On-Hit build by hitting his high AD/Crit builds harder as collateral damage (no pun intended). While the Q buff seems beneficial to AD/Crit Yi at first, you'd have to be in areas that don't have minions, monsters, or other champions within 600 range of your target to make use of the change. This is especially true for players that also play Yi in solo lanes (myself included). Another thing to note is the lack of interaction that PBE guinsoo's (3-hit proc) has with Master Yi's passive (Double Strike); preventing double strike from being procced more often. Seeing as "possible avenues include increasing agency but reducing scaling," I would propose giving Yi slightly more base AD to compensate OR waiting to see if the guinsoo phantom-hit nerf is enough to balance his most problematic build before moving forward with the E change (highly leaning towards the latter).
Link to the reddit article regarding Guinsoo interaction with Double Strike: https://www.reddit.com/r/YIMO/comments/bi6ndy/the_new_nerfed_guinsoo_will_no_longer_interact/