Please do a forum search. There are several threads discussing those lenses. Like this one for example:
http://nikonrumors.com/forum/topic.php?id=168

Hi everyone;

This is my first post on the forums after reading for probably a year or longer. About a year ago I got my first DSLR, a D5000 with kit lenses: 18-105VR and 70-300VR. I love the 18-105VR for a walkaround lens, I love the 70-300VR for birding and wildlife. I also bought the 35mm 1.8 for my new baby girl, and got some beautiful pics with lovely bokeh melting out the background. I do take about 3-4 trips a year to nice locations around North America for other types of shooting, been to the Rockies, New Mexico, Florida, and around Ontario (where I live) shooting all sorts of wildlife, and using my 18mm for landscapes. I will be probably going to Costa Rica for work at least a few times a year starting in 2 months. I also read, alot. I've read almost every part of both Thom Hogan's and Ken Rockwell's sites, and consider myself a quickly learning Amateur. I have a website, and am building up a portfolio of some of my work, if anyone's interested I'll post some samples of what I've been able to accomplish so far. My shot discipline has come a long way, I use a monopod for birding half the time, and hand-held the other half. I take at least a few lunchtimes a week to drive around the outskirts of the city looking for hawks, and have some good pictures to show for it.

To the point: I use the 70-300VR probably 80% of my shooting, mostly for birding, but do other wildlife too, especially when I start visiting Costa Rica.

I shoot probably 85% of my shots on the 70-300VR at 300mm. I'm really starting to feel the limitations of Autofocus speed and the 'softness' of the lens at 300mm. I want to upgrade. My question is, how does this lens compare to the 80-400 or a 70-200 f2.8 w/TC 2.0 III?

The 70-300mm is soft at the long end, and a little slow on the Autofocus for me.
The 80-400mm looks like the same thing with longer reach, however, I've read that the autofocus is slow. I would also have to upgrade to the D7000 for this lens, as the D5000 will only focus with AF-S lenses.
The 70-200mm looks like a huge upgrade, but costs at least twice as much as the 80-400mm once you add the TC. I'm also worried about getting this combo, but finding the loss of light with the TC to be a big factor in autofocus speed, what will it be like compared to the other two lenses?

Can anyone give me experience with these three lenses? I'm debating the upgrade I would get out of an 80-400mm, and cringing at the cost of the 70-200mm w/TC. I love birding, but am really feeling the limitations of the 300mm with softness.

I feel some of my limitations might come from the D5000, but the D7000 is not that much of an upgrade, and costs over twice as much.

And yes, I believe I've read many of the posts on the forums about these lenses individually, but I'd really like experiential comparisons if anyone has them. Opinions with detail would be welcome too ;)