@eboyhou
The Navina has some differences. The retention balloon is considerably larger and seals the rectum better. I was not able to poo it out, whereas the Peristeen can be. Also, the water flow control is a lot better. With the Peisteen, either the water doesn't flow or goes in almost uncontrollably and there is no way of stopping the flow once it has stated, except by releasing the air pressure on the reservoir, which allows back flow of soiled enema water into the water supply bag. This may have been fixed in the Plus version.
And, yes, the ‘supplies’ for either system are expensive. I suppose they are intended to be paid for by insurance or something. There are other similar systems designed to help the disabled with pooing without the retention balloon, but they, too, are costly. Roughly, any of these systems cost between $5 and $20 per poo, if you don't reuse the catheters. The P*I*E cost about $100 per poo.
Also, the pulsing of the P*I*E is mildly pleasurable, but, IMO, the pulsing does just about nothing to make the system more laxative. There was no noticeable increase in urge that I remember. There is the perception that the treatment is, actually, doing something. For a patient in bed the system does have the advantage over an enema that the speculum goes in and the recipient doesn't have to poo on a bedpan, which is not easy.
If you have trouble holding the water while sitting on the toilet, some such system may be a good idea. Obviously, if you have mobility issues, taking the enema in bed is problematic.