I have been reading and have found that Gus Renfro reccomends and uses aspen, Jeff Ronne also uses it I have found.
Gus Renfro- RioBravoReptiles.comMany people have done well with newsprint or another featureless product as substrate. After closely observing captive Boa for over thirty years I myself believe that behavioral problems, temperament and health issues, breeding failures and even appearance-flaws could be alleviated by switching to a good quality wood product as cage substrate. Newsprint may even promote poor condition or obesity. Many larger boas feel insecure crawling on a slick or featureless surface and so will instead coil in a corner or against a branch or hide-box for prolonged periods. Boas are complex in ways we cannot easily see. This includes behaviors. A semi-permanent substrate such as aspen shavings allows them a home-range of sorts, they feel more secure and move about the enclosure with more confidence. Mother boas build nests in the substrate and deposit the young there. If allowed to do so the female will guard and oversee the newborns while they rest and develop for many hours or even days before crawling away with yolks completely absorbed and no bleeding or umbilical problems. There is an observed positive difference in young allowed to develop without interference and it may include a better temperament.
Thats gus's opinion on it all. What do you think. I didn't really like using it with my ball since I didn't notice feces as quick, but if its beneficial I would like to use it. Also if I were to use should I set the warm side temp to the surface temp of the aspen.