In reply to purplemonkeyelephant:
Well apparently they're the thing to use, surely they wouldn't sell something that wasn't necessary, and, they're blue...
But yes, over 10 or more Antarctic expeditions (plus Denali etc) if I didn't use my Primus Multifuel (metal pump) I only used a regular XGK. Early on I did have a couple of issues, one was o-rings shrinking (apparently) and not sealing as well, but this rarely happened. You're much more likely to roll or rip one during assembly.
I think I only ever had one cracked pump itself, which leaked fuel and caught alight, but otherwise the regular XGK pump was fine down to -48C-ish.