Pressure wouldn't be used if it didn't have an important effect on making flavors meld. That being said, plenty of great mixes can be had by simply putting loose tobacco together and mixing it well. Sometimes letting these loose mixes "age" for a while enhances the mix, but often just mixing and smoking work fine. Would the same mix become far better if put under pressure? Sometimes, and other times probably not. I haven't experimented with pressure, so take it for what it's worth, but I often enjoy mixing a little of this and that, in a considered way, and have had some good results.