I agree... I have actually started to play with combining Pre Amp with Attenuation! Its an odd combination for me but I am finding that it helps with noise reduction. I think this is where the ftdx3k really shines over the K3.
You are 100% correct on that. Sensitivity in modern radios is not even an issue anymore, it's now all about getting rid of the extra noise that comes with it.
You can turn the preamp off too. Most of the time I find it completely unnecessary.