Your best bet is to check the historical performance of the flights at issue at FlightStats.com. As with any itinerary, you'll have to make your own evaluation of risk (misconnection and potential replacement flight in economy) versus reward (shorter layover). Since you have the luxury of flying on a full Y fare, if the risk of the connection is too great, then you always can book an earlier AUS-IAH flight, with the trade-off being more time spent at Bush Intercontinental.