i played again with ACR and it is not that bad. although for higher iso i wouldn't like to use it, because the noise is very irregular.
but i discovered another problem. i already saw it with capture one. as you say it doesn't officially support G1 raws, but inofficially it does. because the G1 seems to have exactly the same RAW-format as the LX3 (and D-Lux 4). so if you patch the header of your G1 raws and change them to D-Lux 4 files, capture one opens them if they were normal leica files.
unfortunately the way the lens-distortion correction is implemented is a bit "weak". i don't know if panasonic really thought about what they were doing. but i get much better results if i use an uncorrected raw and correct it with ptlens, than the automatically corrected ACR or C1 raws. today i discovered that ACR is doing exactly the same thing as C1. the distortion correction is not evenly performed over the whole image, but rather concentric areas of the image are stretched. this results in quite inconsistent sharpness, especially if you try to enhance pixel sharpness.