You are a professional and need tools commensurate with your profession.
Some of your points are a little odd. Firstly, why do you say dust is flatter than sand? Dust particles are usually modelled to be spherical or cylindrical in scientific studies, ie the same shape as sand and certainly not flatter.
Secondly, you allude to your professional standard lenses as having a gold ring, and the 15-600mm not being in this class. Tamron used the gold ring cosmetically to designate its SP "Super performance lenses": see - http://www.tamron.eu/en/lenses/technology/sp-super-performance.html for a definition of them and their properties including robust outer design.
The Tamron 150-600mm is officially an SP lens: see - http://www.tamron.eu/en/lenses/overview/single/product/sp-150-600mm-f5-63-vc-usd-5.html?tx_keproducts_pi6[cam]=&tx_keproducts_pi6[vc]=false&tx_keproducts_pi6[sp]=false
The last thing I am going to do is to take my lens apart! If it fills up in the next five years with dust like a Dyson, I'll send it it back to Tamron under warranty.
Yes, let me clarify those points.
1. I should have said that I was referring to dust particles that more than often come from organic matter (i.e. skin cells, fiber stands, decomposed dried plant matter in farm fields during the winter months that flies around everywhere, etc.), in addition to silt size aeolian particulates, as opposed to sand size particles at the ocean that contain quartz grains and other calcium carbonates (so, overall grains that are between silt, sandstone, and higher: 62.5 microns +), which have different refinement properties, and according to the level of weathering, can be angular or round.
2. Yes, I do acknowledge and have no doubt that the optics and design of the inner glass components reflect the SP rating present in the 150-600mm. However, given the build quality and new engineering of the housing components, the "robust outer design" is subjective only to whatever Tamron feels is correct to their design standards. All Canon white L lenses look alike, feel alike, and have a higher standard in material component integration in the designs; however, with three SP Tamron bodies in front of me, it's obvious that the telephoto model has property differences in engineering (outside from the fact that it's supposed to be light and portable) that doesn't reflect the same Tamron series (i.e. Change in manufacturer could be a reason, economic hit on material costs, or trying something new to change their lens lineup, etc.) It's a semi-pro lens and I understand that the market makes portable zoom telephotos (i.e. Sigma 150-500mm, Tamron 200-500mm, Tamron 150-600mm), but like you said earlier, you "need tools commensurate with your profession."
I embrace new lens designs and finding ways around spending $10-$20K on a telephoto; however, I just wish someone would come out with a long range telephoto that had smart and efficient engineering standards that reflected strengths in the optics AND the overall product that cost more than $1000, but still was far less expensive than the big guns.....maybe it's Sigma's turn to come out with a corrected version of their flawed 150-500m or Tamron will eventually come out with fixed long range telephoto lenses in the near future. Until then, Canon is laughing at us all, but gives us some credit for effort!