TG changes. The right way to promote offence.
Ubisoft,
As you can see from many threads here, the changes to light attacks do promote offence and make game fast paced, but with the exception of high level players, it turns matches into spamming match. It is less about guessing your opponent and more about out-attacking him.
I believe you initial idea of giving heroes reactable 50/50 is the right way to go about it. So, a player can react to both actions separately, but when there is 50/50 choice, he needs to decide what to dodge and when. This promotes offence in the correct way.
For example, Highlander vs Black prior. If Highlander decides to opening with forward dodge top heavy, he has a choice: a) do top heavy with hyper armour b) soft feint to the side heavy c) enter OS. At this point Black prior needs to guess what do: a) interrupt Highlander with the bash, but risk missing due to Highlanders soft feints and eat heavy; b) wait for parry, but risk Highlander getting into offensive stance and having more damaging options. d) try to gb him out of it, but risk him landing heavy top; e) light attack to stop him entering from OS, but risk eating heavy from the side or top, if guessed wrong.
This is a healthy way to start promoting offensive playstyle by giving heroes slower, but effective 50/50 options that's based purely on prediction than reaction. Yes, in the example of Black Prior and Highlander, Black prior can react to most of the offence and counter it, but that's just design flaw that requires a bit more fixing. HOWEVER, the idea is correct.
My suggestion is...
Instead of trying to speed up the game by tinkering the light attack mechanics, focus on bringing all heroes to the same level by giving them viable 50/50 offensive choices. For example:
a) aramusha. Let his finishers to be unblockable. This way each time he enters his tempest combo, he has a choice of a) letting unblockable go b) soft feint to the sides c) cancel unblockable into simple heavy/light e) guardbreak.
b) Nobushi: Let her kick be cancelable. So, each time she lands a light or dodges an attack with Hidden Stance, she will have an option to go on a offence with 50/50 attack: a) kick b) guardbreak.
In both examples, a hero will have a chance to go on a offensive with 50/50 to open up defensive player, they will have a condition to start a 50/50 offence, which makes them vulnerable for punish, if an opponent guess correctly (e.g. if Aramusha decides to enter his combo by back dodge light, opponent can back dodge himself or go on an offensive in hopes of interrupting Aramusha, but risking to get hit, if Aramusha decides to continue/cancel-dodge/blade-blockade).
As it stands now, most 50/50 offences are not quite good, because they are either a) easily spammable. b) easily reactable c) don't offer much counters to them. The choices should be either dodge or parry. I find Highlander's 50/50s the faires for several reasons. a) they are not fast, so a person can avoid punish if guesses correctly. b) offers several counters, like dodging, canceling with light attack, parrying, dodge-attack, guard break. c) they require considerable amount of stamina, so they are not spammable, which offers an opponent chance to go on a offensive.
For these reasons, I like the changes to signs (hiding first 100ms), because it smoothes out 50/50 moves and turns them fully into an offence that can be dodged purely through guessing rather than just waiting what happens and reacting.