bag comparisons HELP

[Biloxi]

I am realy having a hard time decideing on the proper bag, and could use some help..my problem is this...I have found a realy nice looking 20degree down slumberjack bag.it says 600+ fill but doesnt give a loft # and looks kinda thin to me,but it only weighs 2.8lbs and I also found a very nice looking north face 0 degree synthetic and it weighs 3.10lbs.I know the 20degree would be ok for a october start but for how long heading north, I am not sure about.and would the 0 be to hot to start with ? I have looked at vapor barrier liners and they can add like 15+ to your bag and would keep moisture from persperation from entering the down. but the trade off there is weight the down and VBL are roughly the same weight as the synthetic 0. but if it were say like 40' the 0 would be hot where the 20' by itself would be ok..also I am planning a thru hike for march 1 anyway and I want a versatle setup. I had also thought of the 20' down with a 40 or 50' over bag ..please help.thx

[mweinstone]

where are you going in october? and for a march 1st start nobo you could use the 20. but if weight is any concern spend more money . marmot uses 850 + and 900 fill down. my bag is 15 and 850+ and 2lbs3oz's and 450 $ . it has an eq coating witch makes it waterproof to a degree.this year my coldest day was 18. i started feb 18th.i had my -20 bag.remember , an overrated bag is never too warm,.. only too heavy. carry as much warmth as you can afford to keep light. get it? any help? welcome to the wb!

[Biloxi]

well in october I am hopeing to do some of the trail from springer to around ashville NC to visit some family around the thanksgiving holidays and after that I may continue on north.I am not sure yet. but I had originaly planned a thru hike for march 1 and was useing this october trip as a shakedown. but if it is going well I may just make it a winter thru. I know I wont be allowed to summit katahdin is the winter, being alone but maybe I could still make it all the way there. at that time I may just turn around and walk home or just go for a while and come home till march and then do my thru. well just wanted some advice on the bag situation. I know both of those bags I mentioned would be to much for anything after april or early may. so I would proubly need another lighter bag. and no I cant see paying 450.00 for a bag .. my whole setup is gonna come in under 900.00