Quote: By removing the filter, you get that sharpness back--but you also have to deal with the image defects the filter was designed to hide. In some types of photography they're not too much of an issue, or you can work to reduce their impact. In the studio you can adjust your subject to minimize moiré in fabrics and hair, for example. In nature, the fine repeating patterns that cause moiré to rear its head aren't so common. (Although they do certainly appear: think hair, fur, feathers, patterns in coloring of flowers, insects, and so on.) Should some defects get past you in shooting, some work in the digital darkroom can minimize its impact, as well. Hence landscape and studio photographers, among others, may be willing to trade off the risk of moiré and jaggies to achieve the maximum possible detail.
Pentax K-5 IIs Review - Overview
The question is do you want the slight overall boost in details you can get with the risk of moire.
It certainly ain't a problem most of the time but if it was just that one in the milion perfect shot that has the moire you won't be happy.
There are way to reduce moire with software but mostly you end up smearing away details.
Also think about how you end up using your photo's.
You won't see the differnce on the internet because of the size reduction and with prints you need to print large and stand close.
Even your old K10D is an awesome camera and with low ISO photos they are stil more then good, here on the web you would not see the differnce either with sharpness.