The draw for the Silo and Silo Special isn't what they use to be. I agree the lack of color options I'm sure isn't helping sales, I would think, but who knows. The just offered the Silo as a BFR and a sparkle rockin machine from what many have said. Colors would make them custom and unless your an artist, black or white it is. Unless you pick one up used and have it repainted to your liking.
While the Silo has been on a low production (legacy) status lately, there have been recent signs of life. In addition to the BFR Silver Sparkle, there are also new Eclipse Sparkle and Pacific Blue Sparkle models over at Sweetwater. Very nice indeed.
Yeah, the Silos are historically important as the first real EBMM guitar model, so they'll never go away. In fact they possibly would have been discontinued some years ago if the it wasn't for their history. White and black are the two biggest selling solid colors on most solid body guitars of any brand, and I would assume the biggest sellers for the Silos too, so that's no surprise.
The Silhouette is a few $100 less than other models. It's nice that you can still get a USA built EBMM for under $2500, while Axis and Luke models approach $3000.
But I'm guessing to keep the cost down, it's a bit more of a no frills guitar.
If you want one in a fancy sparkle finish, you can get one in the Sweetwater exclusive Pacific Blue sparkle and Eclipse sparkle finishes... for about $300 more than a black or white one. Both the Sweetwater exclusive finishes look very sharp.