I now use a Coleman 442 and I love it, It's very easy to use . . . . I used to use a Sportster 533, but I got bought a 442 ( which is very similar really ) and I can really recommend either of these.
I use my stove every other weekend, mostly two nights out (carp fishing) and I drink lots of tea through the day, I bet over the weekend it boils 5 to 7 litres of water, does two fry ups and an evening meal as well.
I've never had any trouble with either of the Coleman's . . . . . I've always used unleaded . . . although I do add a tiny squirt of Redex every now and again. . ..
I also use a Coleman double burner, same there, at least 6 years old, only use unleaded in it, bit of Redex . . . never any problems.
I've also got a Primus multifuel which I do like, but . . . . priming is a bit tedious/smelly and it's quite noisy. . . . at the side of the coleman it gets left at home alot, but I guess it's horses for courses.
The 550 looks like a 442 with different legs, you'll be fine . . .