This article is from the Food Preserving FAQ, by Eric Decker firstname.lastname@example.org with numerous contributions by others.
Very. If you are smoking sausages, excess heat will melt the fat out
and leave the final product dry and crumbly. This I know from
experience. Here, we're talking about temperatures around 140F,
although it varies from recipe to recipe. This is very difficult to
maintain in a wood burning smoker. Mine has a slow smoking section
farthest away from the fire. With experience, I've learned to control
the temperature in this section without overdamping the air inlet. Some
other meats, like bacon and ham, are a little more tolerant of higher
heat, but it can affect the quality of the final product.
The best solution is a thermostat controlled gas or electric slow
smoker like those sold by the Sausage Maker (see sources). These are
not good general purpose smokers, in my opinion. I just don't think
they do nearly as well as a log burning pit for smoke cooking.
Unfortunately for the many water smoker owners, they just won't do for
slow smoking--don't even bother trying.