Tom, I installed a PB105 last December. It's in series with my OB--pretty simple setup, nothing fancy. Out from PB goes in to the OB. Return from the system goes in to the PB. I lowered the OB aquastat to 120 deg. and turned the PB min-160 / max-175. I have 3 forced hot air heat exchange zones, 1 baseboard zone, and an 80 gallon DHW tank. When a thermostat initiates a call for heat, the appropriate existing circulator kicks on. Siince the PB is heating the water, it keeps the OB aquastat over its min so it doesn't fire. If we (my wife) forgets to reload pellets, the OB kicks in. I don't use the outside air sensor. I generally keep the feed around 3. I've found that as I go higher, the auger pushes in new pellets faster than the old ones can burn (as evidenced by partially burned pellets in the ashpan), so keeping the feed rate around 3 produces the most heat with the least pellets. My draft is perfect--checked it myself.
On very cold days, I burn 4-5 bags (I have about 6500 sq ft of living space, and wife/kids in the house all day so generally keep it at 70 deg 24/7 on 3 levels, plus with 4 little kids we seem to have non-stop laundry and baths). On avg temp days we burn 2-4 bags. After long baths/showers, the boiler temp plummets, and takes a while to recover. The normal heating zones though don't have anywhere near the impact on the boiler temp as the DHW.
I've gone back and forth on whether to keep it on manual or auto. Quite frankly, at the end of last winter beginning of Spring, I had set it to manual to avoid the "smoke" problem you mentioned--startup would billow so much smoke that I would just brace for the fire trucks to show up from a call from a neighbor (thankfully, has not happened!). Keeping it on manual avoided all the startups, and all the anxious moments regarding smoke. But, I routinely got the overheat shut down, especially when the weather was warmer--no calls for heat for long periods of time, eventually even the minimal amount of pellets burning would raise the water above the shut down trigger. A dump zone would prevent this--something I'm considering. I figure manual adds 1/2 to 1 bag extra per day.
This fall, I switched it "auto" and tried to ignore all the smoke. As I burned through most of the remaining pellets I had from last year, I ordered from what turned out to be the only source I could find (I live in Mass)--and got 2 tons of softwood pellets (they just say "Wood Pellets" on the clear plastic bag they come in--can't be that good). BUT, I noticed that startup takes around 5 minutes (versus about 15 with quality hardwood), and doesn't "explode" with all the smoke--just a nice quick simple start and significantly less smoke. Hmm, softwood pellets start easier? I tested that theory with the hardwoods I had left (Barefoot)--tons of smoke. So here's my theory: The hardwoods must have a higher flashpoint, so they smolder longer creating more smoke. Try that yourself and see what happens.
Hope this helps.
-Bill