this technique does increase the latency by quite a big deal, doesn´t it?
Yes, it does! This is why CS:S servers running at "tickrate 67" or "tickrate 100" are popular among the low-ping addicts.
On consoles, you typically can't get away with better than 20 times a second (every 50 ms) and many games do it less (every 67 or 100 ms.) Seems to work well for them anyway. The trick is to tune the display and gameplay to work well with whatever your chosen network parameters are.
Okay, so I rely heavily on my client-side prediction, lag compensation and interpolation then. Maybe it´s even a good thing that lag even affects local games. That makes it waaay more easy to test and requires me to work really hard on the networking stuff, otherwise the game will suck for everyone, not just for the guys with slow internet speed.