Ok straight up, the chrono/mule mechanic is far more flexible and forgiving than zerg's inject.
So any comparisons to Zerg are pointless.
But I feel the duration and percentage of the eco boost mules give, combined with the general cost effectiveness of Terran units basically makes midgame (two base) eco based harass of a Terran pointless. If a terran loses 12 scvs they can call down a mule and barely skip a beat. Even the best Terrans struggle to keep their mineral counts down, and that's with the best mineral dump in the game (reactored marines) If a Protoss loses 12 probes, they are often done, as mid game chrono has to go on gateways to keep your army ahead of the Terrans. Any 'fair' (equal food fight) with a Terran will see you lose horribly with him scarcely losing a unit. You have to have a bigger army, and micro better, to come out alive, much less ahead.
If the match enters the lategame, then things change a bit, a protoss saturating 3 bases is nigh on unstoppable, as you can have constant production for 10-12 warpgates (equivalent to 8 rax), you have templars, storm, and amulet. You can even add warp prisms with speed.
And it is at this point you reach parity with the Terran in terms of production and income.
The main issue in the early and midgame is Terran armies are mobile, pack a massive punch for their cost, and produce fast. The two counters to mass mobile terran rax based armies are colossi and templars. Both are enormously expensive, and have cheap terran counters (vikings+reactor/ghosts, which come before templars and can mass before before storm). It's not until you can mass one of these units (temps/colossi) than you can actually get aggressive.
I think the solution, is to cripple the mule mechanic a bit as it will reduce the ability of terrans to mass a lot of **** in the early game without getting an economy going. Say at the moment mules take in minerals at 2x scv speed. Make it like 1.5 or something. Or make the effect last for less time.
Normally massing up tier 1/1.5 units is considered all-in. Hence the 4 warp-gate 'all-in'. For protoss to build and saturate 4 warp-gates means if your army doesn't inflict damage you die (you can't expand). But for Terrans a 3 rax (equiv to 4 warpgates) opener is a perfectly transitional build as they can 1a their initial forces at your base, by the time you've somehow dealt with it, they have the orbital command built, deployed and mule'ing and now 5 rax pumping units to stop your counter push. You are either dead, crippled, still on one base, or at very best, trying to put up your own expo.
Either way, you are behind. And medivacs are 60-90 seconds away.
My solution is to kill the Terran as quickly as possible. And that's usually only possible against significantly inferior players.