Edvin,
Sounds like you might do best with a mixed set. Many people find Pirastro sets to be mismatched with the low E being weak when compared to the rest. They rectify this problem by bumping up a gauge for the E- for example- one might have a stark E and mittel's for the A, D and G, or a mittel E and weich A, D and G.
You may go further down the mixed set road to address your G string problem by trying a different type or different brand of string.
BTW- Speaking of sets you have used in the past, have you noticed the G not blending well with the rest of the set? I find the Flex 92's balance perfectly on my bass. I bring this up because you may experience a similar issue with other Pirastro strings, like the Passiones...also, keep in mind the E balance if you do decide to try the Passiones. They are a great string imho, well worth a try.
One more thing: Taming the G of the Flex 92 set could be a simple as a sound post adjustment too...just a thought.
Best of luck with your search! Please let us know how it works out!
Joe