Most decent gates will also have a facility for deciding how much of the signal youa re gating out. For some styles of music, I find gates do make things sound a little thin or narrow. Bleed is not usually the reason I gate things however. For example, if I am doing rock music and I want a big chunky tom sound, that is not going to come from the overheads, room etc... A lot of that part of the drum sound comes from the tom mics. Even on a well tuned well played kit, there is a good chance that the toms will resonate when not being played. The result is between 2 and however many toms on the kit that may each be resonating their own little tone when things like kick and even snare are hit. Depending on the hardware used to mount the toms and the type of cymbals themselves, even cymbals can set this off. It can create a nasty little chorus of resonance when the toms are at mix level. Gates help reduce how much of that resonance is audible in your drum mix when the toms themselves are not being played. With decent gates you can set them so that when they are closed they are only cutting out 6db, 20 db, all of the output etc... This way you can use them a little more "lightly" without false gate triggers as often. I find them to be like any other tool. Better ones often sound better and are easier to use, cheaper ones often aren't. In the end however, making a bad decision to use one or just choosing to set it up poorly can certainly have adverse effects on your mix. Either way, I do not track with gates. In my opinion, there is no advantage to tracking with them because they generally do not have any dramatic effect on the sound of what is recorded as far as tone and accuracy goes. They do however add the possibility (or probability for that matter) of missing important bits of information (like maybe a soft hit) and screwing up the integrity of the tracking chain. Compression however is a different story. I use compression primarily for tonal changes, especially during the tracking phase. If you are mixing in the analog realm especially, you may have to do some comping in the tracking phase due to having a limited amount of hardware available during mixdown. This could of course be the case with gates as well, but most people who have hardware gates also have enough of them to cover the bases during mixdown. With compression, outboard EQ etc... this is often not the case unless you are in a larger studio.
