I'm flashing with Heimdall and it worked flawlessly with Lite'ning v1.3.
But now I have tried to flash v1.4 and it wasn't any good, I got stuck on the "Samsung Galaxy S II GTI9100" screen (and I'm not the only one).
I started up in Recovery mode and wiped cache and dalvik-cache, but still I couldn't get past that first screen ... Wiped once more and tried again to flash v1.4 with Heimdall, but got the same result.
Afterwards I was able to reflash v1.3 successfully, so I'm able to use my phone again
But I don't understand what the problem is with Heimdall and Lite'ning v1.4?
Could it be because there is a new modem with v1.4?
And would it pose a problem, if I tried flashing v1.4 without the modem?
UPDATE: I can see, that I have Baseband/Radio/Modem (isn't it the same?) version I9100XXKE7, wasn't that I9100XXKE4 with Lite'ning v1.3?
Apperently has my modem been flashed, so guess there shouldn't be any problems in flashing factoryfs.img and zImage from Lite'ning v1.4 ..... or....?