From what I have read it seems the general consensus is that for the best FICO score is to have all cards report a $0 balance expcept for one at less than 9%.(I understand that it varies for each individualy and that for some two cards may be better etc.) My question is can the amount be to low? I have one card that has a $4 monthly fee and was planning on just letting that report every month for my one card. It sucks but that card is my highest limit($1900) so I can live it. But is that to low to count for that FICO bump? I am planning on applying for an Amex Zync this month once my BOA and Chase cards report PIF and want to maximize my score. It's 685(EQ) with those two reporting and one of them is >50%(BOA at 61%) so I'm hoping for a decent bump. I really need my FICO as maxed as it can be as I have two old unpaid CA's from five years that will not be paid, ever.(two apartment complexes for move out charges I didn't agree with. I couldn't pay them then even if I wanted to and I won't pay them now because they are wrong charges) I also have one 30 late from around five years ago as well. I really want in the Amex family and they seem have really lowered their usual standards for that card now so I welcome any advice!
I think that there's no such thing as "too low balance." 
But I understand that you need more than various beliefs.
My suggestion would be that you make all but this one report $0, and let it report the fee. Then do the same next month, but with a higher balance. Compare the scores.
I really do not believe that you will get more points with a higher balance reporting, as long as everything else remains the same (including background stuff that you might not notice, like accounts getting older, etc.) <--This is always the trick with scoring, as there are always quiet movements in the background that most of us aren't aware of.
Look up at the top of this board and click the sticky "FICO Risk Score Reason Codes." There isn't one for too small of a balance reporting.
As long as you have one account reporting a minimal balance, and you've cleaned up everything on your report as best you can, that should result in your best possible FICO score, IMO. But I completely understand your nerves. Good luck!
edit to add: and it's very important to understand that lenders, and this most especially includes AmEx, look at more than your score. They might see a good score and still get the heebie-jeebies at your older history. Any lender that looks at score alone is a fool, IMO, and AmEx isn't a fool. 
Thanks. I know they look at more than scores. From looking at others that have been approved recently I think i have a pretty solid shot. It seems Amex is relaxing their pretty tight standards for this product. I don't have any chargeoff and my credit card and loan payment history is almost perfect, just the one late from several years ago. Once the cards update I'm going to give it a shot.
In my case (a thin file, 2CCs, 1 OD LOC average of 2.5 years old, 4.5 AAoA due to an old TL about to drop off) EQ FICO dropped 15 points 780 to 756 when a CCent from 1% to 4.5 % then another 1 point when the second reported a tiny balance overall Util went from 1% to about 5.4%
So it appears that if you have a clean but thin file you should keep your overall util well under 5%. It could also be that sudden, even small, increases in util could be what's at work. The data is there and it may be used in the model if it proved predictive. I think there is little doubt a one month change in util from 1% to 5% indicates a higher future risk, albeit slight, than a change from 9% to 5%. Almost everyone who defaults starts ramping up their util and occurs subsequently to any ramping down.
