If the founder-CEO is great at sales — not just revenue/product sales, but vision sales, stock sales, and recruiting sales as well — then as long as the “technical” cofounder still likes to sell, you are way ahead.
If your CTO can meet with a prospect and/or a customer and carry part of the conversation, that is terrific.
If your CTO can meet customers at the office and explain why everything will be better, and will be great, that is terrific.
A CEO without a CTO to help her sell is at a disadvantage.
The CTO doesn’t have to be great at selling. If she just wants to help sell, that’s a win right there.