Because you are looking for something that heats up fast I would recommend the MFLB. There aren't a lot of vapes that heat up really fast, but that one can work quite well. I would suggest you read the thread on fuckcombustion about the mflb for more reviews. If its used correctly it can work fantastically, and its not particularly hard to do that, you just have to spend some time experimenting and perfecting your technique. You can buy replacement batteries from the company if they die, and many people buy better (stronger) batteries too.
Because Magic Flight as well as many other manufacturers keep a tight grip over their pricing policies and as such, any retailer selling the Box for below the manufacturers suggested retail price will lose their franchise, so removing the serial numbers hides the ability of MF to trace back to who is selling these Boxes and also will void any warranty.
Lol 20 hits to get a buzz? 3-4 hauls and I'm fucked lol, 5-6 and I take a weed nap. You're doing it wrong. I have had mine for 3 days, watched the vids and I use it like an old pro now.