The two candiates that you have choosen for yourself don't fit your criteria on two factors.
They are both On-Line vs Line interactive and use stepped approximations to sine waves.
That being said neither of those should be a deciding factor for you.
Online vs Line Interactive on a PC is really only something you should consider if you have a lot of dirty power on the mains. Or the device you have wired is super sensitive to power issues. For your computer, its a non issue really unless you want to spend the extra Coin.
The sine wave form 2 years back was a problem. With Enermax in particular and some versions of the older Seasonic platform. If they got stepped sine wave they just stopped working which rendered the UPS null and void really.
Nowadays however that is a non issue as most PSU's can take the stepped sinewave without an issue.
I've done this with the APC's on all the Flextronics Corsair PSU's (of which you have one).
Now if you want an Online Pure Sinewave there is a cheaper Version then grabbing the SMT1500 that Kapt linked.
PFC Sinewave Series - CP1500PFCLCD
THat is a good option.
Or if you trust in what I Say just get a BR1500 + a BR24BPG and you'll get 20min of Run with a feature rich and trustworthy UPS System. Its what I trust all my components to right now. They have not let me down, as it stands I have 200+ events a month that they stop from getting to my PC.
-ST