I agree, you don't want to get into shipping these things. Too much of a hassle now. The best option would be if you could maybe talk HC into setting up a "special" area on their site, that required signing into, so that the packs could be offered separately, at a special price. That way people would pay themselves and HC would do the shipping.
Regarding pack configurations, until the QC is improved, having a 10Ah pack, even using paralleled 5Ah cells, might reduce the number of interconnections, but if a "cell" goes bad it means you've lost twice as much, in terms of replacement costs. Right now, most people parallel packs at the 5Ah pack level, and charge/balance the packs separately. This has one advantage if a cell goes bad, because it won't kill a cell in the second 5Ah pack, unless the balance plugs are also paralleled. It seems that if a pack is going to have a problem, it shows up right away. Once a pack is used for a bit, they seem to stay balanced and work well. If you buy two 5Ah packs and plan to use them in a 10Ah configuration and one arrives with one, or more, weak cells, only that one 5Ah is affected. If you get a prepackaged 10Ah pack, made from paralleled 5Ah cells, and one 5Ah cell goes bad, it will take down the other 5Ah cell it is paralleled with, so it would be like saying both 5Ah packs went bad, not just one of them. I'm probably not making this very clear, but I'm not sure how else to explain it.
I guess there'd also be a problem with doing packs with double the number of cells in series, like 10s or 12s, if there's still going to be an infant mortality issue with these. If you have a single cell go bad in a 12s/5Ah pack, the whole pack is affected. If you have a single 5Ah cell in a 12s/10Ah pack go bad, the whole pack is now unusable. If the 12s/10Ah pack is made up using four 6s/5Ah packs, you only need to replace 1/4th of the "pack".
The QC problem is really more of a factory issue, not something HC can probably do anything about, except to maybe do some pack cycling ahead of shipping. The problem is if any moisture gets into the cell during manufacture. This is typically what causes cells to fail early. The problem is that it usually takes awhile before the problem manifests itself, so the pack might test fine at HC's warehouse, prior to shipping, but by the time it gets over here, the cell(s) start having problems. Cycling a pack a few times should help weed out these "weak sisters", so I would do this initially, before the packs are used.
To me, these prices are so good, even at the standard "list" price (I just bought six Turnigy 6s-5000 20C packs for $60 each...), that it is tough to complain too much about the occasional bad pack. I'd complain more, however, If I had a single 12s/15Ah pack that became unusable shortly after arrival.
What I'm going to do is cycle these packs individually, about 5-6 times, to make sure they are all good, and then I will connect them in parallel, at the pack and balance plug level, and then in series, to make a single 12s/15Ah pack. The parallel and series connections will be part of a single 12-channel LVC board with board-mounted connections for the main pack leads, and the six JST-XH balance plugs. The output of this board will have one set of main power leads, and one 14-pin VAL-U-LOK PE Series connector that will plug into my 12-channel charge balancer. I'm thinking I will arrange the six packs flat, in a 3 x 2 configuration with the leads all facing out. I'll put the LVC board on top, and then shrinkwrap the whole thing together. That will make a very compact pack that is roughy 2-1/2" high x 6" wide and about 12" long, and only weigh about 10-11 pounds. That is tiny
for a 45V/15Ah pack.
If we can ever get past the 50V/12s controller issue, an HC pack configuration I'd like to see for HC packs is a 7s. The reason is that if you use 4.125V as the CC/CV charge limit, as Luke recommends, 7s matches up perfectly with 8s LiFePO4 and 24V SLA packs for charging. So a 14s LiPo configuration would be a drop-in replacement for a "typical" 48V SLA or 16s LiFePO4 setup, and could use the same charger. Three 7s LiPo packs in series, again charged to 4.125V, would be a drop-in for a 72V SLA/LiFePO4 setup.