Well said. You can also consider the various situation you are in when overseas.
I once was trekking a mountain and I had my megazoom with me. I can't imagine if I have to alternate between the different lens and also given the no of stuff i already have to carry, you will thank God for as little additional stuff as possible.
IMHO, get the megazoom (sell off your kit lens) and as you play around with it, you can decide if you need to upgrade to higher IQ delicated lens.
wouldn't you want a weather sealed lens for trekking?
if we were talking about a K-X, my conclusion might be different. go ahead and sell the DAL 50-200. there is a market for them and it is replaceable with lots of affordable alternatives from both pentax and 3rd party.
but we are talking about a K-7. weather sealing is a rather compelling factor to me. if u sell off the twin kit to upgrade, the only other weather sealed lenses are the DA* lenses.
i would keep them and save money to buy other lenses. you lose more money by selling them and going back to either buy the same thing or something much more expensive when u realise that u want weather sealing.