I own a 40D which I use to shoot events. I have both the 30D and XSi and need to sell one.
I am inclined to keep the XSi as it is newer, has more megapixels and features and is easier to use for travel (when it isn't a backup).
Can anyone make an argument for me that this is dumb? That I should keep the 30D? Other than the fact that is shares accessories with the 40D, what other arguments are there?
I can totally understand why you would want to keep the XSi. I like my XT for its like weight and compact size. But the 30D would allow you to have all the accessories the same specifically the remote, vertical grip and battery
If it is more of a backup then the 30D would be the better choice. If you want something lighter for travel, then the XSi. Both are great choices. I would probably go with two 40D bodies given the low prices on them right now.