40khz vs 120khz or 40 plus 120khz US cleaning?

I don't think it's ever been higher than 35c. I do at the most 20 records and stop. The process gets boring quickly. 

Sharpertek said 450 for Ultrasonic and 400 for the heaters.

If you search the internet, you will see that 450W (~41W/L) is a pretty powerful unit.  If the heat-energy balance holds, the tank will heat from just the ultrasonics at about 1F/min.  

I have to wonder if this would be a worthwhile investment being that I already have a 40khz unit?

Without knowing the details of your current cleaning process, and what your goals are, it’s impossible for me to make any recommendation.

Are you using any chemistry with your current UT?

Are you intending to replace your 40kHz or use it with your 40kHz?

What are the details of your current 40kHz, tank size and power?

Do you clean used records or just new records?

How do manage your current bath - do you filter, do you monitor with a TDS meter, how often do you replace the bath?

The purpose of these questions is to 1st determine if there is opportunity to improve what you currently have before considering something new.

Edit - One more question.  How much effort do you apply to keep your stylus clean?  Or, does your stylus routinely pick up detritus that needs to be cleaned/removed?