The Apollo eGo VV appears to be identical to Hoosier Ecig Supplies' kGo VV
KGO V.V. 650mAh I got one of those. Works good! I see some people complaining...but so far I'm good with it when I do use VV...which isn't real often. It's only 650mAh however. I didn't check to see the mAh for the Apollo one. But the passthrough is great imo. You just can't vape and charge if the battery is all the way dead. That's one thing people have complained about. Kinda dumb since that's the way it is with X2s, too. I'm pretty sure you can charge a near-dead battery while vaping if you use the PT with a 2amp wall wort. The other complaint is about the button. It's a bit different. You have to sort of feel around for it. But it's not that hard.
As for the adapters for the Echo cartos on the eGo Twist (I have one of the Hello brand Twists, too from Eric. Works good) You can use a standard sized 510 to 901/808 adapter and put a straight tank collar to cover the threads. Won't be a perfect fit with the Echo carts on the Twist. There will be a bit of a gap. But it works. Adapter is here
510 to [KR808D-1/DSE901] Adapter (you can shop around for prices). The little tank sleeve would be something like this
eGo Chrome Cone for the 3.5 mL Dual Coil Tank Cartromizer Again, you can shop around, but the price on those look pretty good to me.
Personally, I find that I like a voltage level between 3.4 and 3.6...which is what the average eGo styled device is set for, anyway. I have an eGo T Mod that is fantastic...you can run it regulated at 3.4 volt or unregulated..which gives you 4.2 volts when the battery is fresh off the charger..it will work down slowly in volts from there. I use regulated. In the early part of the day I like either standard ohm cartos on my 3.6 regulated X2s, or 2ohm on my little Gripper and on the eGo T Mod. Later in the day...as stress levels peak and I want more punch to my vape, I switch cartos to 1.7 ohm single coil on the eGo batteries (both regular or the Mod). I like Elite 2ml. cartomizers on my KR808 equipment (I get a really wide bore cone from Liberty Flights to make is cosmetically nicer looking on my X2s, but they look fine on the Echo, and they are nearly indestructible.) and I like eGo Mega single coil cartomizers on all the eGo equipment. I use 2ohm 510 XL cartomizers on the little Gripper. I don't like dual coils at all...and abandoned tanks and clearomizers a few months ago.
I DIY my own juice and it's geared perfectly for the equipment I use. If I do use my VV stuff...I use 3ohm single coils and dial up to around 3.8 to 4 volts. Maybe. I don't like a hot vape.