Camcorderinfo.com has just posted a review of the Canon ZR850 Camcorder.
There are a few comments in the conclusions that make me chuckle in regards to choosing the ZR850 or the ZR800

The big choice you’ll have to make is whether to opt for the entry-level ZR800 and it’s mic input, or the ZR850 and it’s better video. This is a tough call. If you’re a new or budget consumer, you might think that you can go without the mic input. We would urge you to reconsider. You’re likely not going to find a better deal on a camcorder with a mic input, which makes it highly compelling. An inexpensive mic will make a huge improvement in overall production quality, probably more so than a slight bump in color and resolution.

This comment illustrates one of the problems I have with reviews at camcorderinfo.com. I sometimes think the get a little too thorough. They tend to place a lot of emphasis on the importance of manual controls, mic inputs etc.

Who is going to use an external mic on a $300 consumer camcorder ?

I can’t remember the last time I saw the average person using an external mic on their camcorder. I never hook up an external mic on my camcorders when I am traveling or shooting for my own home videos. I will use an external mic for paid gigs.

If a person cares enough that a camcorder has an external mic then I am sure they will be shopping for a better camcorder that the Canon. More than likely it will be in the $800+ price range.

The fact is the Canon is a great choice for the regular consumer that wants a nice portable camcorder. I agree that the performance suffers in low light. The picture will be a little grainy if your shooting indoors with nothing more than an overhead or table lamp.