smcFanControl 2.1- good or bad ?

Hello all

First of all , I'll not make the claim to be a " Know it all " when it comes down to computer temperatures, Thus the reason for my posting. I have noticed that my IMac always seems to run a bit on the hot side, so I tried googling normal temps and, what one should do. Seems no matter where and or what I read, I get mixed, incorrect and or conflicting information.

Last night I noticed my temp running a bit high so , I installed and used smcFanControl 2.1 , Now it did what it said and dropped my temp. But, when I did more homework I'm reading this app will cause unneeded wear on my fans,

So know to me it all seems very debatable and, I'm hoping to find the truth of the matter.

Here is my temps from what I first jumped on my Imac




And here are my temps after about an hour



Now if I'm running a demanding app such as Final Cut Express it will get warmer yet.

So I suppose my question is ,

Is there a set of ideal temperatures ?
If so, what are they ?
Would it be best to only run samFanControl, when running demanding apps ?

Thank you all in advance as I make my way through this lack of understanding and , Now confusing issue. If I even have an issue...