It is perhaps more labor-intensive to port a map into TF2 without custom content, but is it really more "complicated and advance"?
With a fully original map, one must come up with a layout, build it, and refine it again and again through the (rather limited) feedback from playtesting. On a map port, one takes an existing layout, recreates it to the best of their ability in TF2, and (in this case) refines it only slightly.
And while you're up on your high horse, I'm going to ask a few questions. Do you have any knowledge of entities and game logic? What about optimization? Lighting? How does the map look in a compile?
Perhaps it will serve as a good introduction to the Hammer editor (my first mapping attempt was a port of a CTF map from World of Warcraft), but in the end, I doubt this map will ever see a release day.