A few of us on the SD card list thread have tried this and it seems to be stablizing things....the theory as we are working with now is that the problem is due to a power control issue in the Samsung drivers for the phone, not especially in the card itself.
No ill effects have been reported as of yet, and the battery life seems to be on par with before the switch was made. It is a simple fix, and can be reversed easily.
I ran the phone for 2 months without a card, and with these keys toggled, it is actually FASTER than it was. I don't fully believe it, but it has been over a week and rock solid.
First off, you need to dev unlock your phone. See the thread here for simple and complete instructions: http://forum.xda-developers.com/showthread.php?t=938106
Next off, you need to toggle the following 3 registry keys in the Registry Editor provided in the above post:
The keys have to do with MMC (internal memory) power management.The big speed improvements is in games/apps (Fruit Ninja opens and operates leaps and bounds faster than it did when the phone did stock!)
HKEY_LOCAL_MACHINE>Drivers>SDCARD>ClientDrivers>Class>MMC_Class>DisablePowerManagement (Change to 0)
HKEY_LOCAL_MACHINE>Drivers>SDCARD>ClientDrivers>Class>MMC_Class>High_Capacity>DisablePowerManagement (Change to 0)
HKEY_LOCAL_MACHINE>Drivers>SDCARD>ClientDrivers>Class>SDMemory_Class>DisablePowerManagement (Change to 0)
Also, I would be interested to hear any theories about why this one made such a big difference when it seemingly affects only the internal storage. Maybe because the two storage devices are "bridged" by WP7?
Comment below with your experiences please!
If this gets enough test results, we will submit it to Microsoft. Thanks!