Is a sucker from a water sucker always a water sucker? Is a meristem clone from a sword / water sucker always a sword / water sucker? Does musa coccinea which naturally clumps like a canna have sword and water suckers?

Water suckers have less vigor because they have a much smaller root system. Genetically, water suckers and sword leaf suckers are the same. Water suckers are generally suckers formed from the root system of a harvested or dead trunk. Sword leaf suckers are formed from the root system of an actively growing mother trunk. The mother trunk is able to supply the baby sucker with lots more energy that is used to grow a substantial root system.

A water sucker can be used to grow a perfectly normal plant, but a sword leaf sucker just has a big head start. Both will result in the same plant eventually. Sword leaf suckers are strongly preferred in commercial production because they establish much faster and much more reliably.

I don't know specifically about musa coccinea suckers, but don't see any reason they would be significantly different than other species.

Water suckers may take a year or more (depending on factors such as climate, soil, the way they were formed on the original root system, etc) to become established, but, once established, should become a normal plant with the same qualities as plants originating from sword leaf suckers. Again, the genetics are the same; it's just that the sword leaf suckers get a large head start in life.

I just googled 'water suckers banana' and this link from discussions at bananas.org popped up as the first result. The quote from an ag professor in the first post seems to agree with what I described. Once the plant becomes established and starts producing offsets (no longer considered first generation), it becomes equivalent to a plant originating from a sword leaf sucker.