RZ 140mm Macro - Advantages?

Just a quick question - I recently bought an RZ67 Pro II with a 110mm lens and I am considering the 140mm Macro for spring flowers of varying sizes. Seeing as the RZ is a bellows camera and can close focus closely with the 110mm, is the140mm's advantage the floating element correction for a flat focal plane, more rather than it's closer focusing abilities?

Considering most of my macro work is at wider apertures, I was wondering whether I would be wasting my money. I use a 55mm lens on my C330f to great effect (for example) as a macro lens and I wondered if the RZ 65mm might be a better alternative as I hear it can apparently close focus to 5cm?

Thanks in advance for any answers.

You are correct - the primary advantage of the 140mm macro lenses (both RB and RZ) is flat field performance.
However they are also both optimized for distances that involve macro and near macro magnification work, rather than for work at greater distances, so when it comes to other aberrations, there will be some advantages when shooting subjects that aren't flat.
I'm not sure you would be likely to see much of those advantages when shooting flowers. I do think, however, that the greater working distance that the 140mm offers (as compared to the 65mm) might be more important than the greater maximum magnification offered by the 65mm. Adding an extension tube might be a better way to get that greater magnification.
I use my RB 140mm lens both for close focus and normal distance work, and it performs well in both situations. I like the field of view it offers.
And from time to time I'll get really close to something with the 65mm lens.

Dear Clapp,
The 140 Macro is a special lens, from portraits to product shots with #1 Ext tube, a great performer....!
I got the LA version, not sure what difference in construction but in combination with 110mm is hard to beat/

Harlequin...

The 140 has a floating element for additionnal correction at close focus, thus the additional ring with ranges covering the standard bellow extension and the N1 and N2 extension tubes ranges.

I recently tested the Mamiya 65/4 K/L lens on my RZ67 Pro for close focus on Fuji Velvia 100F film. I believe it works well for close up shots.