The double helical agitator will mix much more quickly when there is a challenge in the vertical plane.  When you are adding ingredients on top of a viscous product, it can take a long time to achieve homogeneity in the vertical axis with the double planetary mixer.  However, with the double helical agitator providing both downward and vertical thrust, the mixing gets done quickly.  This mixer was formerly used on an 800,000 cP product. The jacket is rated for 100 PSI at 350°F.  There is a National Board number on the tank.

I have this in stock in my London, Ontario, Canada warehouse.  You are welcome to come to inspect this mixer at my warehouse.
Here is the quote:

DESCRIPTION:  Used Ross HSM-40 Vacuum Double Helical Mixer Reactor

USED ROSS APPROX. 40 GALLON VACUUM DOUBLE HELICAL MIXER REACTOR.  THIS UNIT WILL MIX MOST THINGS THAT A DOUBLE PLANETARY MIXER WILL MIX AND IN MANY CASES BETTER AND FASTER.  UNIT HAS AIR/OIL LIFT MECHANISM TO RAISE AND LOWER THE DRIVE TO ALLOW THE REMOVAL OF THE MIX TANK. DESIGNED FOR OPERATION UNDER VACUUM & A POSITIVE PRESSURE OF 35 PSI @ 350°F, JACKET MAXIMUM ALLOWABLE WORKING PRESSURE 100 PSI @ 350°F. MINIMUM DESIGN METAL TEMPERATURE 0°F AT 100 PSI. ROSS METAL FABRICATORS S/N 11801-1, national board 463, CRN 15925. STAINLESS STEEL CONTACT PARTS. JACKETED MIX CAN WITH PROVISION FOR THERMOCOUPLE, INSULATED WITH SHEATHING.  EXPLOSION PROOF 7.5 HP MOTOR, 60 HZ AND NO CONTROLS AS IT STANDS.