Another playfield swap amateur chiming in here. The very first project I undertook in pinball was a complete restoration of my TZ, including a playfield swap. I still plan to document the whole endeavour in a thread one of these days. I can confirm the previous posts: If you have the time, take lots of pictures, have decent tools, and read up on stuff you're unsure about, swapping your playfield yourself is a very rewarding experience. The two necessities I think are worth stressing additionally are space, and organizational skills.
If you have the space to lay-out the components that you're taking off the old playfield for instance, thereby creating a sort of live exploded view, putting things back gets easier. For example, if you have to take off ramps, plastics and posts to get to the pop bumpers that you'd like to swap over to the new field, it helps to keep that ramp, its underlying plastic, and all the posts in their spatial relation to each other when they're off the old playfield. That way you won't mix up posts that might be slightly different lengths, which would for instance change the angle of your ramp when you put it on your new playfield. If you don't have the space, placing all the components that belong to one sub-assembly in its own zip-lock bag can also help preserve an overview of what goes where. But of course, pictures help whichever method you choose to keep organized.
I'd say give it a shot! It takes a lot of time, and a lot of money and space, but the knowledge you'll acquire is most definitely worth it! And hey, if you screw something up, just take it off the new playfield, check your pictures of the old situation carefully, and reassemble.