Reviving an old thread here.. lol.
The X5 spectrum is nothing special really.. growers have been doing it for years with HIDs... usually at a 2:1 or 3:1 hps to mh ratio. Even with fluorescents, at a 1:1 ratio of Warm Whites and Cool Whites. Instead of going through some company to build your light for you, you can use Cree Warm Whites and Cool Whites. The Cool Whites themselves have more lumens per watt than an hps.
Here's your X5 Spectrum:
Here's the Cree XP-G Warm Whites, Cool Whites, and Neutral Whites:
The Warm Whites cover the X5 spectrum all by itself, but mixing with Cool Whites will be better for a higher blue ratio.. making for a more "whitish" light like the X5.
And as you can see... the Cool Whites give off 139 lumen per watt.. that's more than an hps. There's newer Cree diodes out that have even higher outputs too.
Here's the Cee XT-E:
160 lumen per watt... far more efficient than an hps.