I've had some e-mail discussion with one of the guys at Terra Nova regarding the Laser/Phreeranger. Opinions vary (obviously) but it was pointed out to me that the Phreeranger rather than having a higher Hydrostatic head figure is actually much lower. I'd mistakenly claimed that the figures were 8000mm/4000mm Phreeranger/Laser respectively, in fact it's 80cm (800mm) not 8000mm which puts the Laser well ahead.
Apologies for that.
I still think the Phreeranger is a better design though :-)