I got an X-460 for my living room PC a few months ago to replace my S12II-380 (was on sale for $125 I think). Depending on how quiet your other components are, it might be worth it, but I doubt your video card is going to be quiet enough unless you change out the stock cooler.
However, empirically, my S12II was easily the loudest component when loaded up to maybe 150W (Radeon 4830 + undervolted Q8200 + 4 HDDs while playing movies). It didn't sound annoying, but was easily heard over 2xNoctua S12B at 500rpm + 1x800rpm S-flex. The 4830 is passive (Accelero S1). It was probably partially due to being temperature sensitive, as my case runs slightly warm. However, the X-460 eliminates the noise issue and based on most reviews, it is very hardy so running at 20C vs 40C is unlikely to make much difference.
So, if you have a very quiet PC with good fans running <800rpm, your PSU might be the limiting noise contributor, in which case a silent one would perhaps lower the noise ceiling, particularly if you're in the power range; the X-460 has 2 6/8-pin PCI-E connectors meaning it can power pretty much any single card. I have never tried hybrid PSUs (my builds never need that much power), but I'd rather be guaranteed silence than relying on specific conditions for silence; it also reduces the moving parts in your PC by one that is not exactly easy to replace.