Originally posted by natus I will lose... DR on ISO 400-800 and better (???)
Actually, you will
gain DR in almost all ISOs with a K-5 (or II or IIs). The S5 had amazing DR for 2008,
but is edged out by the K-5, particularly in terms of shadow detail (while the Fuji sensor excelled at highlight detail). This might mean adjusting your metering style, but a new camera means adjusting to a lot of differences...
You will also be losing a lot of size and "gear weight" going from the
S5 to the K-5!
Of course, there are also lots of excellent, modern AF prime lenses for Pentax APS-C. Not as many for Nikon... go figure!
Oh yeah, and welcome to the Forums!