Quote Originally Posted by shawn_pa View Post
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What may be problems of using this hybrid oregon 550? I guess I can't have licensed map since I can't provide proper serial number.
Does it have a Lifetime Maps entitlement? If not the lack of a UID may not be a problem. Have you checked the device's GarminDevice.xml file for the UID as well as in G7ToWin? Look at this: [Only registered and activated users can see links. ]. GE uses the UID read from the XML file only I think.

There can be problems caused by incompatible firmware. I can't upgrade.
Yes you can but you have to again combine the US and Korean firmwares and flash in preboot as an RGN. If you try to update with GarminExpress or WebUpdater it will read the Korean HWID and supply full Korean firmware.

These are the problems caused by a hybrid firmware. Am I missing other problems?
None that i can think of presently. If there is too much problem in 'real world' operation you could take the risk and try the flash to full US native fw, alternately firstly with full US changed HWID from 0896 to 1209, and then [maybe or maybe not] try the native fw unchanged. Only you can reasonably assess the risk vs. benefit aspects I'm sorry.