Wrong sort of.
First thanks much for the link! I want one of these, that's about the lowest actaul price I have seen, now I will try to get the HF store that I go to and buy alot of stuff to carry these. Save on shipping I hope. Last time I ordered from HF online I think I had to pay $5 handling besides shipping. Not bad for large orders like I normally place for tools, bad very bad for small orders.
I can't actaully answer your question about the momentary power failure though. For most people that is not that big an issue, they either have power all day or it is out for hours or days. I geuss people like me and you are the ones that have to worry about 30 second power outages that reset clocks and turn off crap remote control digital fans and airconditonares and STUPID chargers (so called smart chargers), stuff that turns off when power goes out 30 seconds or so then does not turn back on when power comes on, I hate that stuff! Only have it because it was cheap off season or needed it right then and only thing I could get at the time. Well enough rants right.
Just look at it often. Why not keep a daily log? Figure it this way, if power is off for 8 hours your monthly usage is not right anyway even if it does not reset itself. If you have no power available then you used none, that does not mean the monthly usage is correct as to what it would normally use for that device if power was always on. So if power is out any extended time at all, your readings will be off for the month anyway.
When I get one I will read it over a set period, maybe daily or every 5 days. Do an average for daily use. Figure the daily average by numbers of days in the month then. Far more acurate that way than hoping the power was not off 7 hours while no one was home to know durring the month. A daily average over 5 days should be pretty accurate. I don't have 100 months to test 100 devices anyway.
If like me you suffer from 30 second power outages (or less) a couple times a day perhaps, then it would be a problem if it reset. My UPS's beeped power failure 3 times today at least, but the lights never flickered that I noticed, it was so fast.
Easy way around that, run the device off a UPS 
Yes, just plug the kill watt meter into a UPS powerful enough to run your loads, plug the load into the Kill a WATT. 30 second power failures no longer a problem
If they ever were.
Hopefully you have one to use like that powerfull enough for what you want to test. I am lucky in that I have been stocking up on Ups's cheap. I have a rack mount 1750watt sinewave Ups $20, I think it would run my freezer or frig fine. 1000watt sinewave UPS $5, 650watt modwaves $5.
In any case unless you suffer the momentary power failures every day (like here), it would not be useless anyway regaurdless, read daily and average several days, skip any day it may have reset.
