Thanks for the info Robert.
I'm going to keep my G20 completely stock (with the exeption of the 3,5 lbs connector I put in it) as I'm not going to shoot the really hot loads. Mostly 180 grain bullets at +/- 1100 fps (which falls between the .40S&W and the true 10mm loads) and some real 10mm loads once in a while: 170 grain TMJ from Fiocchi at 1250 - 1300 fps. Problem is that the bullet selection in .40 FMJ is quite poor here in Belgium and Holland. The only one I found is the Fiocchi 170 grain TMJ. Hollow points are not allowed in my country so most .40 jacketed bullets are out of the picture.
I thought of buying an IGB barrel so I can shoot lead (which is a lot cheaper), but the cost of the barrel is significant (prices are not at all like in the US, don't know how it is in Slovenia) and here in Belgium you need a seperate license just for the barrel, which costs you an extra € 90.
But if I can shoot some 170 grain bullets at 1250 - 1300 fps I'm happy. For some serieus hot loads I use my Super Redhawk: 300 grain bullets at 1300 fps.