Originally posted by Doundounba Besides the crazy expense, I find that, in my experience, there's a point where having more working distance actually becomes a hindrance to good macro lighting. You need an even larger diffuser and much more flash power. While I love my poor man's 1:1 180mm macro (Tamron Adaptall SP 52BB plus 01F) when shooting with a Raynox in the roughly 1.5:1 to 3:1 range, I find the working distance actually a little too much when shooting with just the lens at or below 1:1. YMMV...
My concern with using an overly long macro lens (and I did use an A* 200/4 Macro - but not often enough - for a few years) is that that greater working distance is both an advantage and a disadvantage (it can be a "bug" as well as a feature), and it is not just from lighting considerations.
While it is nice to get far enough from bugs so as to not disturb them, and it is nice to have the ability to occasionally get macro shots of flowers that are somewhat high off the ground or rather far on the other side of a fence, etc., this advantage comes at a price. If I am trying to shoot something from somewhat above, I need to get a stepladder (which I don't usually carry it my kit bag) to be able to get far enough above the subject (or take advantage of a convenient porch or steps, etc., when available on occasion). I have found, when using a long macro lens, that most shots are constrained to be sort of horizontal shots (which is fine sometimes, but which is also a requirement forced upon me sometimes too, simply due to the long working distance).
My most used macros are the A 50/2.8 Macro and the Tokina AT-X 90/2.5 Macro -- the working distances are quite convenient for me nearly all the time. I might occasionally use a Vivitar 28/2 Close Focusing, but lighting/shadowing can sometimes be problematic with it. I also might also occasionally use a Vivitar 135/2.8 Close Focusing, but the working distance can sometimes start to be constraining for some subjects in some locations.
So, I am just trying to point out another consideration from using a longer macro lens. Obviously, due to the subject matter and shooting style, YMMV.