after some feedback

No I stayed in RGB.

I didn't get any wierd color halos, but in lab mode you would want to only sharpen the "L" or Luminosity channel, in RGB mode as long as you use a alpha channel to make your "smart sharpen" mask and you sharpen on the composite channel you shouldn't get halos, perhaps white and black halos, but not colors.

Lab mode is cool though, have you tried removing grain in lab mode? It works really well, just convert to LAB and look at your A and B channels to see which has the most grain or noise, then run "Dust and Scratches" and play with the radius until the unwanted noise is gon then play with the threshold until the film grain is back. then convert back to RGB and look at your image. I like this technique, but I don't often get a photo bad enough to use it.

Yes, but you'll have some (sometimes minor) color shifts if you go to LAB...
Fading the sharpening to Luminance has the same advantages!

I often find that fading changes to the luminance blend mode in RGB screws with the colors in the image too much, I'm not entirely sure why though.

Checking a couple of different pics and alpha channel and Luminosity channel are basically the same when compared together, so no real need to convert to LAB.
For sharpening purpose, the differences really doesn't matter either.
But in RGB mode you also have the 3 colour channels (duplicates) you can work off also, to really narrow down where you want the sharpening to occur.
And to make things more complicated, you could also use your favorite b&w convertor, and copy this into an alpha channel, then find edges etc.

thnx also for the noice reduction tip. This was going to be my next question ;)
Two photographers I teach do often get photo's bad enough to use this.
Not their fault, but "sport photos on overcast day with slow lens using digital camera" type of fault.

For noise reduction, check out this free action: http://www.2morrow.dk/75ppi/coolpix/actions/

And for channel splitting, look at http://photoshoptechniques.com/forum/showthread.php?s=&threadid=7163 the action will give you H,S,B,L,A,B,C,Y,M,K and other channels in addition to the RGB ones!

thnx sPECtre, delux noise reduction is COOL!
even on heavy jpged pics it worked, and my hi-rez photos worked well also.
Can't wait to try on photos with digital noise - and increase my street cred ;-)

Will try the other colour splitting action tomorrow, when on other puter. snds really interesting, with only briefly readying the post.

just wondering CryptoManiac, if in LAB mode to do noise reduction, is it safe to run the dust and scratch removal on the lightness channel?
For me, my pics come from a scanner, and no matter how much I clean glass etc, there is allways going to be dust.
Initial tests on L channel dust removal seems ok for removing pure white dust, but again, maybe there is something I cant see on overall picture.

Also to keep to original Unsharpmask question, the action for channel splitting is awesome, to give you even more channels to work with, when finding edges to sharpen. But I bet you knew this sPECtre ;)

Maybe, crazy camel ;)

About your dust problem, if your technique works, why asking? ;) don't forget to look at prints for the definitive result! sometimes, you need to stop trusting the monitor!

lol...good point sPECtre. I did stop trusting monitor long time ago.
On the other hand maybe I should also trust it as well.
If I can't see it, maybe it isn't there :D

It should be ok to run on the lightness channel in small amounts, but remember that the lightness channel holds all your detail, so doing too much will result in a gummy picture.

I love the delux de-noise, my only wish is that I could have a little more control over it (I'm sure that by studying the sction I could learn to get more control.) It seems to do a fantastic job with small amounts of film grain and digital noise, but I have some images that need more of a kick in the pants and being able to bump up the values may help out a bit.

I also Like all the edge actions, by studying them I have started to make a few of my own edges, we'll see how they turn out.