Is the american bass vfl 1000.1 stable at 1ohm?

It appears to be just two of their 500.1 amps in one casing. Depending on how they have the two amps wired internally, you'd want either a 1 ohm or 4 ohm load on each set of terminals (top and bottom). If it's like normal strapping of amps, you can put a 1 ohm load on each set of terminals.

I guess what I'm asking is can the 500.1's handle a 1/2 ohm load?

I think you can go as low as 0.25ohms / amp with those. I know some people are using them that low.

0.5ohms / amp shouldn't be a problem.

I guess what I'm asking is can the 500.1's handle a 1/2 ohm load?

YES 1/2 ohm daily eazy ( with good power ) ALL the vfl amps will.

Is the american bass vfl 1000.1 stable at 1ohm?

YES

Scratchy Ba..... I mean American Bass.