Welcome to FT!

Most times you try to swich FF miles between programs, you will get hit with a large devaluation of miles, as you stated.

Also, as you stated, due to the large number of partners and alliances, it is easy to accumulate miles into a specific program so you can use them for awards.

And don't forget - with the numerous alliances, you can use the FF miles from one program to fly on another airline (in that alliance) ! Just this past September, I had to fly from PVD-PDX. I wanted to reduce my NW FF account. Of the 5 flights that I used, 4 were on partner airlines (DL and CO) - but I used only NW miles!

So unless you really want to take the large devaluation, I would not recommend a transfer of miles.