Will ultrasonic cleaning in general be a noticeable improvement over the VPI? Thanks for your help
That depends on your technique and the cleaning fluid. If you use AIVS enzyme fluids, and do several rinse steps, you can get records reasonably clean. The VPI is a mediocre vacuum but useable. The issue with this method is the amount of time it takes to clean a single record plus it's messy.
Ultrasonic cleaning can take less time and depending on the setup you choose, can clean multiple records at a time. Again depending on your setup, fluids and methods Ultrasonic can give excellent results.
Re: Kirmuss - it's pretty close to the bottom of my list.
For discussion on the Kirmuss and other RCMs:
https://www.whatsbestforum.com/forums/record-cleaning-and-related-topics.393/