SCHUBERT  If you use Photoshop as much as I do, the question is not "when" do you need a masking plugin, the question is "which one" to use. Akvis Smart Mask won this battle of the masking plugins hands down.

I tested OnOne Mask Pro, Vertus Fluid Mask, and the new Akvis Smart Mask v2.5.

All had similar features, with the exception of a few important items which I believe sets Akvis Smart Mask apart from the competition.

1. Memory - Akvis did not strip the life out of my MacBook Pro, as did the others over a period of time. When tested equally over a 30 minute period, Akvis was the only plugin which did not cause my MacBook Pro to run hot.

2. Quick and Clean Interface - I personally like the interface of Smart Mask much more so than the others. It loads quickly, it is easy to navigate, and it responds almost flawlessly.

3. Price - Again, Akvis Smart Mask wipes out the competition, no need to rub salt in the wounds of the others.

All in all this is one fine program which does what is says and more. Save yourself time, effort, and money... try it and buy it... thank me later.  
(Version 2.5)