HEPA filters are great, but they are expensive. Water filtration is so much better than HEPA & costs the price of a quart of tap water. While HEPA may get 99% of dust & dirt, with little leakage back into the air, water traps 100% of the dust & dirt, with ZERO leakage. I don't worry about seals & such, as the dirt goes from the hose directly into the water reservoir, becoming mud that does not aerosol.
Because HEPA filters are so expensive, one is always tempted to postpone a filter change, which means the filter is not working as efficiently as when new; perhaps not at all. No way to know for sure.
With the Rainbow, the water "filter" is easily changed before EVERY vacuuming, & the "filter" is always brand new & working at top efficiency. Adding a few drops of scent to the water makes the house smell nice. I can use the vacuum as purely an air cleaner/freshener.
Plus, the dirty water shows you what dirt has been removed - proof the vacuum is working properly, & if something valuable gets sucked up you can easily retrieve it from the reservoir.
No, I do not sell Rainbows, but I'm glad I bought one. (Now, watch it break down next week - it's pretty old).
I have had Rainbows demonstrated a few times, but I just don’t see $1200 sitting there when I look at one. I’m sure it’s a good sweeper, just not worth it. We have an inherited Kirby now that dims the lights for the entire block when I turn it on - seems to pick up way more dire than our old cheapo Dirt Devil did.