Whatever you want but Billy Goat has video where the "Force" blows a cinder block farther than anything (and other objects). They compare LW and2 or 3 others.
The warranty I don't know about but I personally had Billy Goats that ran until they literally fell apart from everything wearing out (axles, handles, motor mounts, wheels) BUT they had never broken down once and were still blowing fine. I never threw one away. (We are talking 17-18 years old and no more than spark plugs, oil, and starter ropes. (and 1 set of tires)
I owned 4 from 11hp (now 13) to 16's (now 18) and not one ever broke down other than things like the ropes & normal engine maintenance. So a warranty was never needed.
The BG video is at
http://www.billygoat.com/site/forcevideoDisplay.aspx?vid=2
and you are more likely to be blowing things on a flat surface than a ramp.
Also if you don't know the Force has an adjustable discharge nozzle. If you look
very closely at the LW video on You Tube the Force nozzle is set all the way at the "high" position where almost 1/2 the air goes over the flat thing on the ramp.
If it was aimed at the target (handlebar control) like the LW is (manual control) it would do much better I'm sure. But you have to know how the machine is made and
look very closely at the black adjustable nozzle which is hard to see in the video.
And BTW, how did we get OFF TOPIC from 5's for1 man & driveways (which LW doesn't have) to 9's
PS: I'm also in the D/FW area & never used anything but BG so I was using them several years before LW's came on the scene about 5 years later and were originally offered because they were a good bit cheaper.
Also if you didn't care about "1 man" I would get the BG 13, they are the best for "all around" use. Big enough for commercial but can be turned way down for drives. BUT the OP was about a back pack compared to a wheeled blower and LW isn't in that market.