In reply to JayPee630:
Ice Guide uses the inferior Primaloft Eco/Silver (like just about everything else they make now). Spitfire One was Primaloft Gold. I snapped one up just as they were disappearing; I don't like that they use the cheaper primaloft. I haven't used it in anger yet though.
Ice Guide is also quite a bit lighter (200g)? They also seem to have switched from the beefier Pertex Endurance [Mini] (bit more water resistant) to Pertex Microlight [Mini].
It's hard to tell but I think maybe there is also less insulation in the Ice Guide (nothing below 170gsm in the Spitfire, 133gsm in the Ice Guide) as well as the insulation being poorer, which might also help explain the weight loss? I wonder if they decided the Spitfire was just too bulky.
Post edited at 15:25