I might be able to help you here, I have a Chelsea brought from same supplier about 5-6yrs ago. First I brought stove delivery excellent[4 days,] is installed in my house, got clip in boiler as well[2wks delivery]. it heats one rad in b/room & small towel rad & heats water. performance is very good use semi smokeless[Burnwell] & wood[has multifuel grate] no problem keeping fire in 24hr am very pleased, think you will find rating is 'up' to 5kw. One gripe is airwash is not very efficient, but just clean glass in morning when emptying grate & done, ashpan sufficient for 24hr use, empty grate once a day.
Have a Squirrel on boat had boat 11yr works very well good heat & 24hr use easy, did overhaul 3yr ago, new flue, glass, fire bricks, sealing rope & repaint, no boiler as no rads, as boat is trad have b/mans stove in rear cabin. Find Morso sufficient for heating boat, do use fan on top at times and it doe's move heat to rear, but stove is 10' from front of saloon so more central installation is to my mind a big plus.
As to which is best must admit am well pleased with both stoves, main difference being price & difference between cast & steel, have had no trouble with Morso cracking[stove was on boat when purchased so don't know age]. you do know you can buy refurbished Morso stoves, friend of mine got one & no problems.
in my opinion both stoves are good for boat use, both give excellent heating qualities.