Comp as a Senior at a Private Investment Bank vs. Public Investment Bank. Help Please

Guys and Gals,

I currently work at a pvt IB which allows senior IBs to buy in at book value. This works great since the ROE has been very high lately and has proven to be a very effective tool in retaining talent (voluntary turnover has been less than 5% for the last two years).

My question to you guys/gals is how public IBs protect its talent from leaving to a private IB without this great incentive. For example, most publicly traded IBs trade at ~2x's book and thus for any given employee your ROE is effectively half the percentage it would be at a private IB. How are senior IBs compensated at your banks on top of the bonuses? Any ideas?