Anyone own an Elgato HD60 Pro?

I've been lately thinking of treating myself to a HD60 Pro since I just got a Nintendo Switch and have been wanting to really stream games like Super Mario Odyssey and the like but have some concerns before I possibly buy.

The HD60 Pro fits in a x1/x4 PCIe slot, right?; but does this cause any noticeable performance degradation if compared to having it slotted in a x16 PCIe slot? I might want to get a HD60S instead but would prefer to shoot for a HD60 Pro if I can. Also, I'm not sure if my rig can handle the heavylifting from both streaming and recording or either at times but also that it uses your GPU to do the heavy lifting, graphic processing wise as I have a somewhat old rig...AMD Phenom II X4 960T, GTX 650 and 12 GB of DDR3 RAM.