I vote no for now, appendix later.
I guess that for most Chapters, their fleets will pretty much be the same (that is, probably quite small!). I think that if there are enough options to make a working/interesting fleet-based chapter list (e.g. Lamenters, Dark Angels etc.) with all of the typical Space Marine ‘goodies’ (good boarding parties and so on) this will have plenty-enough variety to simulate different chapter fleet-philosophies.
The other more ‘cosmetic’ stuff, like ‘Blood Angels like to bash stuff! +1 to boarding values’ (no offence to disciplined, shooty Blood Angels) or organisational changes won't be necessary for the basic list so can wait for an appendix to be done properly.
Although I'm not really sure what one would do with Chapter Traits…. Inspiration from the Badab war, perhaps?
Plastic Space Men for thought (a reference to the Goodies
)
Thinking Stone