The idea behind lowering the vent pipe inlet to grate-level in a pit with SFB is that it aids in keeping the heat flowing near grate-level instead of above it, where it would normally travel without lowering the vent. This should reduce grate temp variances from end to end, somewhat, but it should allow you to increase the draft for a bit more even heating...this may come at a cost of higher fuel use, but allows for more use of your grate space for similar types and sizes of meat.
As for achieving too little smoke flavor, you just need more smoke output to compensate for higher flow/draft through the smoke chamber. The main concern with smoke is to keep it flowing...stale smoke can cause a bitter taste...which is why many of us want to keep the vent fully open, or nearly full open. That's not to say you should never close it down a little for temp control, as each smoker has it's own personality and likes to run with the inlet/vent set a certain way for given conditions. Target chamber temp, ambient temps, wind and precipitation, as well as how much mass of cold meat in the smoke chamber will all have an influence on preferred draft settings. Then of course, as the meat's surface heats and less thermal energy is being absorbed by the meat, you find the need to reduce the draft somewhat...it's the fire tending game, if you wish to run constant temps.
As with any manually controlled smoker, you will need to experiment/practice with it to find where it likes to run at your desired temp. Your gauges should be at grate-level. Higher up in the smoke chamber on a pit does not give a good reading. Short-stemmed gauges won't give an accurate account of the temp near the center of the grate, unless you have done some serious internal mods, such as tuning plates, and have verified those temps during normal smoking conditions (loaded with meat).
For the most accurate grate temp readings, a digital pit probe does well, or you can use a higher temp capable digital meat thermometer, with the probe at grate-level, next to your meat.
Don't forget to check accuracy of your therms periodically....here's a elevation/water-boil temp chart to determine what your therms should read in boiling water at your location:
Boiling Point / Atmospheric Pressure / Altitude
Hope I covered everything...if not, just shout back.
Eric
