Canon 100mm/2.8 Macro IS vs Canon 85mm/1.8

I currently have the old Canon 100mm/2.8 Macro and I'm considering upgrading because the AF suppose to have been improved. I will be using the lens for close up shoots and possibly portraits.

How useful is really a macro lens for portrait work or is 85mm/1.8 better for that kind of photography?

Consider the new 100 macro IS L lens. The 85 f1.8 is great for the price, but the purple fringing can be very annoying.

The new 100L kicks. What would the advantage to you be with having the extra stop and a third the 85 provides? There has been a number of portrait shots posted using the 100L since it came out. There is no issue with using it as a portrait lens if that's the FL that will work for you.

i have both. i prefer the 100L due to:
1) IS
2) close MFD
3) much more comfortable FL on FF.

but in dark situations, it hunts.

so i figure, i'll try the 85 again with a flash or two.

It sounds like it will be the 100L, thought of getting both if the 85 was better for portraits. I will most likely not use it in low light situations, if that's the case I can use a tripod.

Anyway, thanks for the advice

I don't have a long macro, but I am not crazy about them for portraits. A fast lens like the 85f1.8 will let you manipulate sharpness by altering aperture. It is good wide open for portraits.
My needs may be different than yours - I am older and may take photos of older folks or younger ones with blemishes. A macro lens may give you more sharpness than you want to deal with, even wide open. If you don't mind extensive Photoshop, any macro will do.
When I use my 50 mm macro for portraits, it is never stopped down and it is used wide open. I generally try another focal length for that purpose. The 85f.8 is also fine for head shots and really good for fast action shots outside.

I have heard before that some think a macro is too sharp for some portraits but I don't see this is as a problem at all. I love working in Photoshop so it's quite easy to fix if I want a softer look on my portraits.

My biggest concern was the DOF and bokeh, for portraits I want the "pop" effect. The only one that I have seen that really does this is the 135L, the 85L looks very nice too but not within my budget at the moment. I thought the 100L would be a good combination of macro and portrait.