I can speak for the Vortec swap. I do the swaps in my shop. It has been said before and I will say it again, a properly tuned and maintained 1FZ will take your truck long into the future, albeit at a slower pace than the highways of today dictate.
The Vortec swap excels in three areas, parts supply,reliability and longevity. The bottom line on these engines is that they are fleet motors designed to be a work horse, thus the iron block and subtle other differences from their LS brother. The taller intake manifold works to build more low end torque etc. The parts supply for these motors is unequaled and only challenged by that of the original GM small block. What this means for the swapped rig is that in the middle of Kansas when your water pump lets go you can find them at most any place that sells parts and the guy down the block can install it for you.
To address pricing, I can tell you that my swaps run aprox $10K in parts alone, that does not include custom parts I make in house. Like anything else you do with your rig, you can do it to last a couple years or a lifetime, it is all up to you. You can do it for less in parts, but every corner you cut removes time from the overall life of the vehicle.
There are always those that hold the position they would not pay that much for a swap to an $8K rig. Valid point, but if you invest that kind of money in a swap it would only make sense that you would also be rebuilding at least the running gear of the truck as well. The whole idea is to build a reliable daily driver that will continue to serve you well into the future and give you all the benefits of an LC while off road as well. You can build out a smokin 80 for say $35K There is nothing out there in the new market that even comes close that is under $55K.
It all comes down to what role you want your LC to fill. If it will always be the 3rd vehicle and not have to do DD duties etc it may not warrant the expense.