First off, I'm a noob vaper so take my advice for what it's worth
I definitely wouldn't say a Vapcap was stealthy, having to heat it up is going to look fairly obvious.
Background - skip if you don't care
I've only just registered but I ransacked these forums before I bought my first proper vape, I chose the Fury 2 and while I don't have anything to compare it with, I'm seriously happy with my first 6 days vaping.
I've smoked since I was 16, tobacco and weed, always wanted to quit the tobacco part (it tastes disgusting and it doesn't even get you high, who came up with that crap?) but I've never been keen on pipes, can't afford to smoke blunts of skunk all the time. 40 now and tried a friend's vape, a fury copy, and I was amazed how good it was. Little research brought me here and I found out a few things that convinced me the fury 2 was worth paying extra for over the copy, for example the copies have to be taken off charge after 2 hours apparently because they don't have auto shutoff and it'll screw the battery. I'm a stoner. Who gives a stoner something that has to be remembered or it breaks?!
I had been cutting down on cigs and increasing my weed, so last week I was smoking around 10 joints a day with about 5 cigs in them, I switched to just vaping weed and not only have I saved the cig money, I'm smoking much much less weed than I normally do. I was trying to keep it down to 1/2 oz a week and usually failing. In the last 6 days I've not even vaped a full 1/4 oz, my guy texted asking if I was alright because I haven't ordered.
Actual vape stuff
The Fury 2 is total stealth. It's practically invisible in my medium sized hands and if people see it? Does not matter. With the popularity of Ecigs lately, nobody gives you a second look when you're walking down the street puffing smoke from an electronic device, might get a muttered 'douchebag' occasionally from hardcore smokers at worst.
I haven't had a problem with the battery yet, but I haven't really been out using it a great deal and I top it up as often as possible using it at home. I don't see it being a problem though because it has a micro-usb charging port - I can use the 10,000mh xiaomi power pack I bought for my phone to keep it charged up and ready. The power pack is actually slightly bigger than the Fury 2 but still easily pocketable.
I see people making the distinction between session and on-demand vapes and I don't really get it in this case. I stick my hand in my pocket, click the button 3 times, wait maybe 20s (25 officially but I vape at 190 mostly, seems to get there faster) then start smoking. It's quicker than I can roll a joint, so maybe I don't understand the terminology yet but it's certainly on-demand enough for me. As tfrank already said, hit it while it's cooling down to clear out any last bits of vapor and also help it cool down a little faster if you're refilling. I find I can get a couple of sessions out of a bowl at 190c and still be getting good vapour, according to a vaping temperatures chart I found on here I'm just leaving mostly sedative effects behind at that temp. So my ABV goes into ajar for when I can't sleep.
Fury 2 worship done, I'm considering buying a vapcap M for emergencies/power cuts/the inevitable zombie apocalypse (will YOUR vape survive being covered in brains?) ect and I expect to love it given the reviews here, but there's no way I can use it as casually in public as the Fury 2 given it's not legal in the uk.
I'm also looking at the E-nano or maybe one of those Ed's Woodscents Aromalog little maggie above just mentioned if they ship to the uk.
TL;DR
Fury 2 good for stealth, but everybody should get a vapcap as backup. You don't want your battery to run out when you're hiding from zombies and need a hit and the zombies have eaten the power-plant workers.