[Marc Sabatella]

No reason to be, but on the other hand, I'd say the Pentax 55-300 is probably the *best* telephoto zoom, and the 50-200 is also nice in that it is inexpensive and much smaller and lighter than any of the others. But as you'll see if you search/browse there forums and read any of the hundreds of other threads on the subject of telephoto lenses, the Tamron and Sigma 70-300 are both pretty popualr too - they are usually the cheapest options, and aren't bad at all.