I have had the SVD from fasttech for about a month now and really enjoy using it, although for practical day to day use I take my MVPs (also FT) because they are totally hassle-free, last for ages and will even charge my cellphone if needed.
The SVD is beautifully made, fairly heavy, and works perfectly for me. Battery life is only a few hours of chaining, though. It's an excellent synthesis of a mech mod and a VV/VW device. For $37 at FT (just the SVD itself), it's definitely worth trying out.
Are you using this battery? Panasonic NCR18650B Super Max 3.7V 3400mAh Rechargeable Li-ion Battery-Green