Hi Rapidboy,
I like mine. I've only used it a couple of times but each time was with a fire and I had no problem with sparks.
They offer a groundsheet for this tent but I'm not sure that I'd take it if I had the choice again. Having tried the lavvu with and without the groundsheet I've come to the conclusion that these tents really do work better without.
Flame retardent - it certainly seems to be. I've checked after having the fires and not noticed any holes due to sparks.
BTW, I'd recommend the firebox from feuerzelte if you need one:
http://www.feuerzelte.de/shop/show_det.php?det=47&nav=33&rb=34
Once going it takes a reasonable size log and I found that you could keep it going all night with only a couple of refuels.
Having got used to the idea of no groundsheet I'd probably look at a Kifaru or Titanium Goat Vortex next time around - more tent for the weight (or less weight for the tent). However, I am very happy with the Helsport.
Cheers,
Huon