I've got a 2 burner SMEV stove cut into the tailgate kitchen, and I love it. The ability to pull up, swing the tailgate and click in the gas hose is priceless - you find yourself stopping for lunch by the side of the road and cooking sausages, etc. It's all self-contained, you can't leave any bits behind, it's just easy.
When we bought our trailer, it came with a gas certificate. From memory, talking with JT, it wasn't strictly necessary for QLD, but some other states it was. Anyhow, to completely avoid the hassle they had all their trailers inspected and certified anyway. That may have changed. On ours, the gas bottles connect via flexible hose to a regulator (hard-mounted to the camper), and then a quick-connect coupling. The stove has a long flexible hose on it, which clicks into the quick-connect when the tailgate is open.
Father-in-law recently replaced his 3-burner portable stove with a SMEV unit same as ours. Basically for the same reasons as us - it was an ease of use thing. He wanted just to pull up and connect the gas, and be ready to go. He had a mobile gasfitter come out to install it, and was told "why did you get me out mate? Just do it yourself - these are the bits you need". He ended up hooking it all up anyway, but it was just a long hose with a POL fitting on the end to suit the gas bottle.
I've recently gone off our little cartridge cooker. I love it completely, but I don't love the cartridges. Specifically, I don't like disposing of so many of them. They're cheap enough to buy, it's more of a philosophical choice around going camping to enjoy the beauty of mother nature then throwing 2 or 3 cartridges into landfill.
Anyway, to answer your original questions:
1) Cost - shop around. FIL bought his SMEV on line, and it was hundreds of dollars cheaper than the local caravan place. Also hundreds of dollars cheaper than some other well-known online sites. Do your homework here and reap the benefits. Still, more expensive than a portable unit.
2) Safety - I think that's already been well answered. You probably don't need to get it certified, but it might be a good idea. This only covers the plumbing for the stove, they don't look at the quality of the stove at all.
3) Workmanship - don't really know what you're getting at here. I'm going to answer by saying if you stick to a good, well known brand (Like SMEV, which a lot of us have and are happy with) then the quality should be there. If it's not, make sure you're familiar with the vendor's return policy.
4) Quality - no idea about particle control. I do know that there's a difference between jets for LPG and natural gas cookers? When we got ours there was a big brouhaha about the glass lids not lasting in an offroad camper trailer. I think that myth has been well and truly busted by those of us who have used them offroad for a while now without any damage. I don't doubt that they could break, and I always close the lids at camp so they can't get blown down, but I've not yet seem one that broke in transit. I would suspect the Particle Control story is similar.
If I were you, I'd be more worried about whether you want a 2 or 3 burner, and how close the burners are together (IE, can you fit your billy and fry pan on at the same time). Lost's stove is a big 4 burner (I think?) and huge, but lets him use the stuff he needs to use. That, to me, is a more important design choice than anything else.
Also, without knowing exactly what was going on in his head, I doubt dazzler meant any disrespect. I would suggest he was just presenting an interesting argument that you could regurgate to any inspector who may be quizzing you on why you don't have a gas cert. IE, "no officer, this is a portable unit, because...". But hey - never let me get in the way of a fight between a newbie with 8 posts, and a well-respected senior member who has a history of being as helpful as you could ask...
Anyway, good luck with your decision. I don't think there's a bad choice here - just comes down to how you want to use it and how much cash you're willing to sink into the camper.
Cheers,
Matto