vac u flush

I had both
The "Half bath" (restroom) was a Sea Land type Gravity. Step on the pedal and gravity did it's thing

The "Full bath" (included a phone booth shower) had a Macerator or Vac-u-flush type. Push the button and it fills up some more then WOSH it's pumped to the tank amidships and then it fills up the rest of the way.

Dead batteries=no flush
There are supposed to be sensors to tell when the tank was full.. Never installed.

That was fun.

I have the Macerator Style on my Southwind, and have had to have it worked on three times, and once it breaks the underneath smells wonderful :)

There are 2 types of remote Toilets
1. TRUE Vac u Flush, uses a remote vac pump to "pull" the debris from the toilet thru the Vac Pump small reservoir and then forces the waste to the remote Black tank. This uses very little water, usually about a pint per flush.
2. The 2nd is a Macerator style pump system, that uses plain force from the pump in the toilet to get the waste to the Black tank. This is the most common remote RV toilet used
3. The Vac u flush I have only seen in Fleetwood Motorhome products, but I know others use them. The disadvantage to the Vac u Flush is, the down pipe from the toilet to the Vac pump is only 1 inch in diameter. Then it has a larger hose from the Vac pump to the Tank. I have worked on just 1 and it was because the down hose from the toilet was clogged. REAL PIA to work on because you have a few qts of sewage water to deal with. Then they usually install the Vac pump in a inaccessable area under the main floor.
4. I would opt for the Macerator toilet rather than the Vac u Flush.

I would prefer a macerator toilet to the vacu-flush system. Fewer parts and less space needed, but the tank can still be almost anywhere. Of coourse when the tank can be located directly below the toilet, it's hard to beat the standard RV toilets for simplicity.

In some floor plans (those with 2 bathrooms) the vacuflush system is the best way to handle waste and keep 1 black tank. Another benefit is that the tank can be placed just about anywhere and that helps weight distribution.

Ours has been relatively trouble free for 13 years with the exception of having to do a bellows replacement last year. That is a pretty standard expectation for wear and tear for this part.

When we bought this motorhome, we thought the 2 bath was a little excessive but we loved the floor plan. After living with it for 13 years we wouldn't be without a 2nd bath given a choice.

The standard RV is a simple gravity system. The waste tank is directly below and when you push the pedal, a trap door opens and everything falls straight down (or pretty close to straight). Very simple and not much to fail. About the worst thing is the seal on the trap door can wear out.

Vac-u-flush is really a marine head (toilet). On boats it's actually rare to have the tank directly below the toilet and on sailboats, you could be at a 20-30degree heel. So an RV style toilet doesn't work. By using a pumping system, they can force the waste horizontally or even uphill.

In some RVs, it's not practical to place the waste tank directly under the toilet, so they use a marine head. Having had these on boats, I would not want one if there was any other option (in fact, we replaced the one on our boat with a composting head...a different subject all together). They tend to be smellier and are far more prone to failures (A leaky seal on an RV toilet and it's a nuisance but you can still use it until you get it fixed...If pump on a marine head goes out, you are done using it until you can get it repaired). Also, they tend to use much smaller 1.5" diameter flexible hoses which are prone to clogging and given a few years, odors start going right thru the hoses.

I wouldn't necessarily rule out an RV that has one but it's not a selling point.

Looks like a trash pump. More parts used, more parts to break. Uses more space too.

https://marinesan.com/vacuflush/vacuflush-toilets-generators-info/