A clamp meter is a great tool! If trying to track parasitic leaks or corrosion leaks inserting a DVM in the negative battery lead and setting it to the 10A or 2A scale is going to be more accurate than most cheap DC clamp meters that I see owners use. The small Extechs offer 10mA but many companies don't publish DC low resolution numbers so it can be guess work. Good companies like Extech and Fluke do..

The Extech 380942 is one of the tools I use in corrosion & marina surveys but is way more than most would spend or need for low resolution DC clamping. It is a small 30A AC/DC clamp but it sells for close to $400 due to its low resolution accuracy. It saves me a ton of time however and is extremely accurate down to 1mV DC.. Yokogawa also makes an excellent leak detecting clamp meter but again these are beyond what the average boat owner would ever need.. My Fluke stuff has been bullet proof, I beat the piss out of it. While offering good accuracy the Extech stuff ihas not proven to be as durable. My Extech 380942 has been back to Nashua twice, and I baby it compared to my Fluke stuff.....

For starter/motor loads most DC clamps can not perform an in-rush function because they are not fast enough. Some may even claim to have in-rush capability, such as Mastech (or any of the other names that cheap Chinese meter is sold under) but the in-rush is really only for AC). To get the best idea of starter loads, with a standard clamp, pull the stop cable, close the seacock and try and watch for an "average". With digital meters this can be tough to garner but brands like Fluke do okay and you can develop a feel. I own the Mastech MS2108 and it has been a complete POS. At this point I just leave it in a drawer on my brothers boat... Horrible accuracy and a crappy case design. Not all cheap clamps are reasonable quality but every now and then you can find them.

IMHO a decent value in an AC/DC clamp, for DIY DC use, is the cheap Uni-T UT204A. I ordered one for a customer and I was reasonably impressed with it for the price. Better case than the Mastech and better accuracy. When you zero out DC it actually stay pretty close to zero...

http://www.amazon.com/UT204A-Digital-Display-Multimeter-Voltmeter/dp/B00CO2G0NI