Looking at the Amazon reviews, the Rapid 2200 with cutter rather than
cogs seems generally to have good reviews. I think I'm going to give it
a go and then post a review, giving suitably grumpy warnings about the
confusing change of number. The "modern" 2200 is significantly cheaper
than the cog based 25 D Quiet.
That's what we bought a while back after quite a bit of deliberation.
Part of the logic was the cost of replacing the 'blades' on the
turbine or cog versions, v the fairly simple flat blade type.
In use it's effectiveness and efficiency really depend on two things.
The shape and density of the material being shredded and the sharpness
of the blade(s).
We first took down and pretty well entirely shredded the greenery of a
conifer of some sort. Daughter and her b/f then trimmed off and
stacked up everything smaller than about 1" in diameter and I fed it
though the shredder. When I say 'fed it though' that was mainly just
standing a length (or two / three, if thin enough) in the hopper and
the lengths just seemed to fall though. I was chipping it straight
into 'garden bags' are there are two projections onto which you can
hook the handles of the bags (there is quite a draught blowing through
the shredder as it's part of the motor cooling cct). So, the biggest
issue there was how fast it could fill each bag!
If it ever get's overloaded (too much at once or a particularly hard /
big bit) it cuts off and you just have to turn it off and on again. No
need for reverse, you just take the load off the blade, restart and
off it goes again.
If it does jam (and it hardly ever did on the conifer) it's just one
long threaded hand screw to open the entire front up and access the
hopper / blades etc (the 'hopper' is actually split in two with the
front off like that).
The next tree was an old crab apple. That wasn't half as easy because
it was extremely gnarly and miss shapen (no nice long straight runs
like the conifer) so the biggest task was threading the stuff into the
mouth of the hopper. Secondly, much of it was dry / dead / stick-like
and sounded more like you were planeing a length of dowel than
shredding greenery. ;-)
Again, and *as long as you keep the blade sharp* (I kept a fresh edge
on it with a diamond sharpener every few hours or changed the blade
over maybe once in a days work) and were a bit selective what you put
through it, it worked very well.
For the rest ... brambles or general leaves and other garden waste ...
again, the long straight stuff tends to fall straight though, the
bulkier more leafy stuff required the use of the plastic 'pusher'
(supplied), but again, rarely clogs / jams with that stuff (although
it does need more 'feeding' that the sticks).
As I said at the beginning, blades are quite cheap, can be found
easily in most sheds and are quick to change (pozidrive screwdriver
and two screws). The problem with all these devices is when you get a
stone in there and how then you finish your job with a £100+ 'blade'
that's now mullered? ;-(
So, we think they are brilliant. Not the quietest or highest capacity
things in the world  but with the right stuff they are pretty fast
so you won't be out there with it on all day (although we worked ours
8 hrs a day for three days straight and it was faultless). Definitely
wear hearing protection, goggles (stuff can whip round) and gloves.
YMMV of course.
Cheers, T i m
 Both the kids are tree surgeons so are used to 'proper' 6"+
'chippers'. Both agreed this was a good bit of kit for the money and
size / weight etc.
p.s. We typically ended up with:
Chogs (mainly the trunk)
Logs (sections of branch)
These we given to people to store / burn.
Sticks (A bit too big to go through the shredder, took to the dump or
wete taken to burn)
And many many bags of shreddings where we used some for compost and
stuffed the rest in the green bins. ;-)