I got the 45's and started taking apart the pipe tonight.
First thing: there is a lot of creosote buildup in the stove pipe after ~1 cord of well seasoned wood. Not sure how much to expect, but we have been doing a lot of running inactive because of the short burn times. I bet the rest of the chimney is equally coated and limiting the draft like it seemed the past couple weeks.
Second: I'm pretty positive the smoke/creo smell is from the DSP adapter. The major sign is that there is quite a bit of deposits on the
outside of the flue collar and the outer wall of the adapter is very loose and essentially wide open. The smoke can easily make it around the outside of the collar connector and unless there is very high draft it seems easy for it to start seeping out around the base. It could also pull a decent amount of air from around the collar and the elbow at other times when the draft is strong.
Third: The 2ft DSP pipe fits very nicely onto the collar (both inner and outer walls) and these installers could have easily used the 3ft section they brought and my hole would have been a ft higher. I said "why use that?!" They said "Oh...you're supposed to use this adapter".
Will update when I get everything together! Looks like I will have to cut some pipe to bridge between the two 45's but the good news it that I will only have about 6-9" of horizontal run. I'm really hoping it runs well after all this!