Most dual band HTs don't have dual receivers and the duty cycle (not to mention the limited battery life) further limit the HTs ability to perform this function. However, here's a thread from eham.net that discusses this topic and makes some recommendations (it's a bit old though).
handheld/mobile w/ crossband repeater capability? - VHFUHF Forum at eHam.net
This thread from qrz.com also discusses this topic and has some more recent entries that may be useful.
do all ht's have crossband repeat? - QRZ Forums
The reason I asked was that the impression from several folks that asked about this previously had the impression that both the HT and mobile radios had to have this functionality for them to use it. Since you're familiar with this cabability, you know that this isn't the case.