What is that makes the Jabsco inferior?
The short answer is, "disposable" is more profitable than durable.
toilets, unlike household toilets, have moving parts
that do require at least a little maintenance
and occasional (every 5-6 years) replacement of some parts
. However in recent years toilet mfrs that are divisions of large diversified companies have been steadily moving away from quality and durability and toward "disposable" equipment
Someone at Jabso even admitted to me that their manual toilets are made to be "disposable"...that the service
kits are overpriced because there's no profit in repair parts, but there is in complete pumps. They're so flimsy and failure prone that an amazing number of people just replace the pump every year as "PREVENTIVE" maintenance
(There's a guy on a sailboat list who's done that every year for 10 years. I've kidded him about being the only person I know who's put $1000 into maintaining a $100 toilet!). Jabsco isn't alone...Shortly after Thetford bought Wilcox-Crittenden, they discontinued W-C the Skipper
and the Imperial because there isn't enough market for a $1000 MANUAL bronze "throne" built to last for at least 100 years and not enough profit in repair parts to make it profitable even to continue making the HeadMate...so they discontinued the whole W-C product line at the end of '08 for that reason. And we've seen the Tecma line deteriorate in quality since it was acquired by Thetford.
The only US toilet mfrs left except for Jabsco are Raritan
and Groco, both of whom are still small family
owned companies to quality and durability still matters.