I will disagree here. First, the shoes are the same price at retail, the exception being for special makeups that would put a premium in the price (a la ultimate indy).
That said, I love my 405s. The leather feels much softer and thicker to me in my hand than chromexcel. Both are great leathers, and you should only decide based on which boot you like better. Chromexcel is a pull-up leather that will accentuate the aging process and wrinkling; while the 405 will obviously wrinkle, it won't be emphasized as much. Also, chromexcel color may initially transfer when it gets wet, so that can ruin some pants.
Clarification: Brown Chromexcel is indeed the same price as the brown cowhide. Natural Chromexcel generally seems to be ~$40 higher. A worthwhile upcharge, in my opinion.