Well, I said I wouldn't post my thoughts until I had used these for 48 hours.  I changed my mind.  I want to note some initial impressions.
My initial impressions are very mixed.  I only ordered three of these.  The first one out of the wrapper has bad threads and will not screw on to any eGo or eGo clone I have nor will it screw on to any of my 510 extenders or adapters.  Since this has a skirt like the eGo-t or eGo-mega, I can't actually see what's wrong with the threads without cutting it apart.  -  1st one bad.
2nd one - better.  It threads on to a genuine eGo battery and any of my extenders or adapters just fine.  However, the skirt bottoms out before the 510 connector can make full contact on every eGo clone I have.  I have a couple of no-name eGo clones I got in the classifieds a while back, and I have a smoke-tech black battery that says "SMOK" on the top, and I have the gold-ring eGo clone that madvapes sells.  The skirt bottoms out on all of them and they can not fire on any of those batteries without using a 510 extender/adapter.  Using an extender sort of defeats the purpose of using an eGo-specific design.  You may as well just use an extender and put it on a mod.
Capacity:  I just got in some 10ml bottles of flavors I haven't tried from BWB.  The advertized capacity is around 5ml.    I got about 3.7 or 3.8 ml in it before I noticed juice dripping out the bottom all over my desk, my keyboard, and my leg.  Initial fill capacity is closer to 3.5 or 3.6 ml than it is 5 ml.  -  As with most polyfill cartos, I think the filler will become more absorbent after a fill or two, so maybe they'll hold 4 to 4.2 ml.  I haven't measured the height and circumference of the filler to figure it out exactly, but I do not think they will ever hold 5 ml.  4ml is probably it.
Vapor Performance:  Here's where things get better.  I was able to get these to work on standard genuine joye batts, and with an extender, I tried them on a couple of mods and also with an extender, i tried them on a couple of eGo clones.  At 3.2v on a genuine joye eGo batt, they produce at least as much if not more vapor than an eGo-mega that's working properly.  That's very good.  They produce a lot of vapor at 3.2.  --  They surprised me at 3.7.  The vapor was thick and warm almost as good as a standard dual coil at 5.0v. That makes the fact i couldn't get them working without an adapter on my eGo clones pretty disappointing because it would be a really nice match if it worked ( I can see a scenario where a small amount of time with a file could make these work just fine on an eGo clone like the ones I have, but out of the box, this is just unfortunate). --  I just got a 5.0v triple-v out of the classifieds. So, that what I tried these at 5.0v with.  It produced a cloud like I've never seen before.  I will most certainly be ordering a couple of 510-to-ego adapters so I can use these cartos on my triple v and have it look nice at the same time.  All I can say about the cloud of vapor is "WOW".
Flavor:  Here's where I screwed up.  As I mentioned, the juice I used was a flavor I've never tried before.  I have no idea what it's supposed to taste like.  --  The flavor I used in he carto I'm testing is BWB Malty toffee.  At 3.2 on the genuine joye ego, the flavor is a little weak.  At 3.7 the flavor was better (more potent), I suppose, but again:  I've never used this flavor on any other device, so maybe I should just quit talking about it...  That was not a good choice to be able to share my thoughts.  The remaining carto that I haven't used yet will get filled with a flavor I use every day, but that's going to wait until tomorrow.
Other topics I'll mention when I return to this in a couple of days:  Wicking, and whether or not I think they'll last.  I may even attempt a cleaning on this first one after I've consumed this 10 ml of malty toffee because that's all I have of that flavor.