nikon 200mm f4 micro
Where/how do you do macro photography that "taking it with you" is a concern ?
If you like to have the option to do an occasional macro shot while out & about shooting other things, then the 105 (or extension tubes or a close up filter) might be a better option.
When I was doing nature photography (before my daughter came along and I turned into more a people photographer !) I had a Minolta 200/4 macro (I was shooting 35mm film then). That lens focuses internally, so gets to 1:1 by a combination of extension and zooming; at 1:1 it's closer to a 135mm lens than a 200. I found that to be a very good FL for giving me some working distance and a narrow enough FOV to control backgrounds. I've always assumed that if I got back into macro photography, I'd use something in the 90-105mm range on APS-C, though preferably a lens that does not focus internally, so that it maintains its focal length. I'm not sure if I'd find a 180/200mm to be on the long side. I pretty much did macro or didn't do macro ... that is, if I went out for a morning with my backpack full of gear, I'd leave the macro lens behind; other days, I would go out with the camera, macro lens and tripod and no other lens. I find macro requires a different way of looking - it's hard to find good subject matter when trying to look both close and far.
The other benefit of the longer macro lens is the rotating tripod collar. That lets you compose a shot then decide you want vertical instead of horizontal (or vice versa) ... without the rotating collar, you have to flop the tripod head and your composition is shot. The rotating collar also provides a good place to mount a sliding rail, not a necessity, but very handy for getting precise compositions as you focus.
Finally, I would seriously consider going with a used manual focus lens, unless you really want to use it for other purposes. Trying to get what you want in focus without stopping down unnecessarily is best done with manual focus, and manual focus is best done on a lens designed for it.
A few old macros (slide scans) done with a 200/4:
Gallery at http://kingofthebeasts.smugmug.com