The right-of-repurchase grants that I've seen have always been 83-B grants where the company lets me buy all the stock up front so I can start the tax clock. The right of repurchase lapses on a vesting schedule, just like options.
From that perspective, there isn't much difference between (A) Vesting Stock, and (B) Lapsing over time a Restricted Repurchase agreements.
Nobody is going back on their word - it's just a different way of vesting.
I agree. In addition to the 83-B election, I've seen a right-of-first-refusal for share repurchase. (Third party offers you $X/share for your shares, the company has the right to purchase at that price instead.)
I've never seen a "we can repurchase shares as we see fit" clause.
From that perspective, there isn't much difference between (A) Vesting Stock, and (B) Lapsing over time a Restricted Repurchase agreements.
Nobody is going back on their word - it's just a different way of vesting.