I think it is up to you.
As you can see from the replies above some people like mechanical fans and some like electric.
I think both have their place, I have used mechanical fans, and I plan to use an electric fan on my project as a mechanical one won't fit.
For those of you with the idea that mechanical fans don't fail check this out:
Blade I was in the middle of Yosemite National Park when my 52 3800 threw a blade, not my idea of fun while almost 3,000 miles from home. I was able to get by until I found a replacement fan later in the day.
Fan Balancing You have already spent money on the electric one, and sounds like you want to use it, or you would not have installed it, so use it. if you are still not sure it was a good idea then put the mechanical fan under the seat with a wrench and a set of bolts.
