I purchased a 4Gb TopRam miniSD from Ebay nearly a month ago. Inserted in phone straight out of the box (already formatted) and was good to go. Have filled nearly 2.1 Gb of its capacity thus far.
Only issue(s) I've had are basically just 2:
1) If I install anything loaded on the "Today" screen such as "WeatherPanel", ect... or any other auto-polled App on the miniSD = Random DSODs
2) Tried the PIE "Cache to miniSD" hack and that produced = Random PIE crashes so reverted that back to phone memory.
PS: Currently running Verizon Rom V2.07.20 WWE and the "Unbranded Phone - Hard Reset" hack and only adding a few of the Verizon customizations back. Been tempted to flash up to one of these 3.5s but now that I've cured my DSODs for the time being, a little hesitant.
Oops
Had to retype this post about 4 times until I finally read the disclosure about not posting links until your 3rd post or something... Anyhow it was Ebay Item #140116233643 from seller
kofkl