Powerline
Powerline
You might notice a slight reduction in speed when moving your PC to a higher location, but it's unlikely to be dramatic. Powerline typically adds only a few Mbps, so you could expect around 4-5 Mbps loss rather than a major drop.
It all comes down to your home's wiring and the distance between the adapters. I've experienced poor performance in mine—typically around 3-5 Mb/s even when conditions are good.
I've rolled the dice, but I've also faced some bad luck with them. They tend to be finicky, don't always work right, and can be slow.