I'm on CS3 , and have been a light photoshop user, but of late what more skills , particularly in the mask / matte area.  Anyway, I went through the McLeland videos as well.  I assume you are referring to the channels and masks series ? Anyway, wow, that was quite an  eye opener for me.  Seeing just how many steps and skills it takes to get more complex pictures masked.
Anyway I was determined to continue in my efforts and then I tried out OnOne's Mask Pro.  Now I'm still experimenting with it, and I've gone through the Lynda.com series on this plugin. It's a short series of tutorials.  Anyway, take my opinion with a grain of salt only because I lack both the experience and professional level of a serious photoshop user. 

I think this product can save considerable time.  It's not magic and learning how to adjust the options on the fly for each area is a learned skill. What I am noticing is that for someone like myself it makes edge work far easier, meaning I am seeing less mucking with the edges as I did with things like color range, selection tools, etc.  I've tried it on some grayscale images and channel masks and again there things seemed to go smooth. 

I'm open to hearing more opinions from others, particularly if I'm losing anything from using this plugin versus just staying within Photoshop. Seeing Deke's videos opened my eyes to the challenges and art of masks and paths.  He is very meticulous and following along wasn't easy. On the other hand I now have at least have a better understanding now of the process. 

SA