Meanwhile I figured the Tg of the PLA/PHA material was about the same as regular PLA.
In fact, I discovered an easy way to determine the (approximate) Tg temperature: just put a piece of filament on the heated build tray and then heat it up. As soon as Tg is reached, the material is getting really floppy like a string of rubber.
This is then also the right temperature to set the bed (or possibly a bit lower) while printing. The floppiness of the material will make sure it sticks very well.

I still have about 8 kg of ABS in my filament rack, but nowadays I almost print everything with the ColorFabb material.
The WoodFill is indeed also great - the filament breaks easier than the regular PLA/PHA filament. I can break the WoodFill by hand, leaving a nice straight edge that I can feed into the extruder. The PLA/PHA really requires a wire cutter otherwise it is hard to break. Still, after cooling down the WoodFill forms very tough objects. The material has a very good layer bonding and is hard to break.

Flame polishing (I mentioned this before somewhere else) works well with this material. To get the best effect, don't overdo this or you will get a plastic look, a small torch at a low setting will reduce the layering that is already less visible than with normal plastic materials. Unfortunately I am still having problems printing WoodFill on my Leapfrog Creatr with the standard 0.35mm nozzle (ColorFabb suggest 0.4mm or bigger) so I am going to drill a nozzle up to 0.5mm
Don't leave the WoodFill in a hot extruder too long, it really becomes a messy goo substance that may be hard to get out: the oily substances in the wood settle to something that resembles accroides gum.

The _XT material is also very nice, it gives a nice shiny glassy texture to objects even more than PET does.

Too bad ColorFabb has no water soluble material yet but I heard they are hard at work to find a solution for this.

Rob