Yes, I did it on my Traditional Chinese Dopod 818. Bluetooth is much more stable w/ the 1.11 WWE Rom (no more Bluetooth hardware not found so far). The tradeoff is 2-3 mb less in main memory since I need to install Monster Chinese and Input method since it's an English rom.
My SE X1 rom-> http://forum.xda-developers.com/forumdisplay.php?f=471
Actually, my machine is originally a Worldwide English (WWE) Imate Jam (most machine sold in US is Imate Jam, which is the same hardware as Dopod 818 and Xda II mini). I flashed it with Tradition Chinese Dopod 818 rom 3 months ago and flashed it again w/ the patched rom few days ago. (I also change the splash screen to my Doggie's pic)
As U can see, the OS Rom version is 1.11.00 WWE which is latest one U can get. (Latest one for Dopod 818 is 1.06.00).
Radio rom come with the patched rom I think is 1.11 (for 900mzh GSM) but I flash it seperately w/ US radio version 1.10 (for 850mzh GSM). I have no way to verify if it really works or not since I am living in 1900mz GSM area.
U don't see ExtRom version since there is NONE. (Copy out the software from ExtRom before apply the update, in case U need it later.)
U can see the Storage is now 26.72mb instead of ~7mb
For Rom w/ 1.11 only, Bluetooth added a new tab with devices which assigned a COM port.
So far, the machine runs very stable. And as I said before, I don't experience "Bluetooth hardware not found" anymore. (used to have it quite frequently w/ 1.06 Rom) Therefore, I recommand either use this version or wait for 1.11 Traditional Chinese version come out.