He's talking about the RX 460, not GTX 460. The RX 460 is marginally more powerful than the R7 265. Also please don't use GPUboss, it's terrible.
Here are actual benchmark results where the RX 460 comes out slightly ahead of the R7 370, which is a rebadged and higher clocked R7 265.
OP, it's not really worth replacing. It's not an upgrade you'd really notice in practice.