I would generally appreciate if Mongo would write more about his experience with the lens (all other aspects). I had some trouble with the long zoom throw that generally was very slow to move for example. In the end I exchanged the lens for the 4/300PF because I had to much trouble and was generally demotivated to carry the 2300g while the 750g of the 300PF are with me very often.
Frank, Mongo wrote a review of the lens last year. Since then, everything in that review has held true. The only additional matter is that Mongo now thinks the collar and foot assembly is overall, not adequate for the long term.
Your purchase of the new 300mm f4 was a very good alternative even though Mongo thinks the new 300 f4 is over priced. Mongo has used one and found it to be a very good lens. Only disadvantage is the shorter reach and, if using converters, the hassle of taking them on and off the lens. Having said that, Mongo still goes back now and then to using his AFS version of the 300 f4 with converters (x1.4 and x1.7 when he wants a lighter combination to carry. This gives very good to excellent results and Mongo would expect that your newer 300mm f4 would give even better results.
hope this helps
