I've got a Yammy AW4416 which is like the big brother of the 16G. I've had it about 8 months or so.
As mentioned previously they are good units - I'm happy with the dynamics although I'm no expert, not entirely sold on the EQ however and I'm presuming it's the same as on your machine.
One thing I'd definitely recommend with these machines is outboard preamps as someone else said further up. I've got a Mindprint Envoice and Presonus MP20 and although these are firmly in the prosumer range, you can absolutely hear the improvement in quality. Hard to explain exactly, but it's there. As well, the Yammy preamps don't have a hell of a lot of gain.
My 2 external pres are useful because the 4416 has a couple of insert points on Ch 1/2 to bypass the inbuilt pres - again, I presume the 16G has the same.
The thing you have to think about with external dynamic and EQ units like this is how you get the signal in and out. Once it's digital it's probably best to stay that way, and the 4416 has ways of getting the signal in and out so it stays that way. If you go out and back in via analogue means then you've added two conversions to your signal which may or may not override any benefits of a better compressor etc. A digital interface on any devices you're considering is a definite plus as it solves this problem.
If you think that buying a Behringer compressor, sending the signal out an Omni out and back in through an insert will give you a better result then you may be disappointed. Hop on over to one of the Yammie boards (
www.socialentropy.com/aw4416/ is the main one I hang out on) and you'll get advice based on your particular machine on things like this - they're very helpful over there (not that you guys aren't here, of course!)
Cheers
David