Really liking the FW4. Heater is as fast as other portable convection units, software is nicely tweaked from FW3, even the buzzes are just a little shorter and noticeably less audible. I love the set-it-and-stare-at-the-horizon interface, and now the heater's so fast that all the guesswork is gone, just draw slow and enjoy.
Form factor is huge. Very small and light, solid and precise, the machining on the battery cover is really impressive. After a couple Firewoods, I feel like walnut is THE proper wood for a vape now. Beats my Milaana for fill-capsule-and-go portability/compactness and discreetness.
Effects are similar to FW3, but the speed and ease make for a clear upgrade. Extraction excellent, I like daytime low-temp sessions and I can milk a half-capsule for 8-10 hits at 1 or finish in 4-6 at 2, and finish a nice even brown.
The cooling unit is nicely effective, the small tube is well matched to the draw speed. @ 2 I don't mind drawing native, currently I prefer using a glass Crafty mouthpiece for a little less cooling and a wider airpath than the cooling unit (I'm used to the more manual breath control of a bigger mouthpiece).
Marc sent me an xtra bit of walnut to make a custom setup for the Crafty glass, I'll post pics once I have something. Sorry to those who have to wait, but this is lean manufacturing at it's finest, a refined design made by a craftsman, plus direct contact for customers, it's so cool we get this kinda support, and nice to think that Marc is getting paid ok for his efforts.