I bought one Generac online from Amz about twelve years ago, still going strong, no issues. Decided to get a larger unit and bought that one online at Loews due to better selection and picked up locally when it was shipped in. One subtlety about buying larger items like gensets is "power tail gate" delivery vs "loading dock."
Being in a rural area with a two hour drive to major urban shopping, online is a fact of life. We've had no "DOA" issues. The one thing I haven't bought online is a TV, though I've noticed when UPS or FedEx pulls in and the door opens, lots of flat screen TV boxes. :-)