[davidmanze]

Hi Dave-

Right again!  I live less than a mile from the ocean.  Sometimes you do get a break an the thermal heat waves if you are shooting across the water, since the water doesn't heat up the way the ground does.  But in general, yes, at shorter distances a teleconverter seems to work better than long distances.  I'd just like to see what the 800 could do with a 1.4x, or a 2x.  

There have been a few sightings of unusual birds here where that combination would be great if it worked well.  For my purposes the 90D with the 100-400ii + Tamron SP 1.4x tele has proven to be a lot of fun.  Maybe a Sigron 150-600mm would be better for distance shots...but I do love the easy handling of the smaller lens!  You know how it is in the back of my mind the question is what next?  I will be eyeing these new lenses.

I know there is a lot of pent up demand for lenses like this, if the performance is good.

 I think the maxim of:  "try before buy" would be in order here!