I have had some contact with several hunters that upgraded from the F2/F4 platform to the F5 and have read posts from many more.
Sometimes it is a smooth transition, but sometimes the advanced features and the amount of settings available has thrown a few new F5 owners for a loop.
I know one that loved and got very good with the F2, upgraded to the F5 on my recommendation and kept sending me PM's about how unhappy and frustrated he was.
At the 2 week mark he was ready to throw this thing into a lake and be done with it.
I kept telling him to stay with it, the learning curve is not the same as it was with the much more simpler F2 but his patience would be rewarded.
He did and not soon after he settled down and everything fell into place and now he loves it and has found some great things and still uses both units but the F5 is his prime and he is very happy he upgraded.
If you really want one there is lots of info out there.
The best is what we call "The F5 Bible", which is a compulation of tips and tricks put together by a guy named Sven who took all the info he could find posted by a very capable and successful hunter named Mike Hillis.
He is a guru with many detectors the F5 included.
You want to get into the F5 or just know how it works...a must read.
http://www.mediafire.com/view/r2mm2fv2ymt7ose/F5+HUNTING+TIPS.doc