Houston HD signals on 1800'+ towers reach at a minimum of 75 miles. HD on 104.1 will be fine in NOLA and BR in the car and spotty in buildings.
Cited examples: KIOL-HD...reaches from Sulphur, LA to Katy, TX. KTBZ/KLOL/KHMX/KODA et al reach from Missouri City, TX to about 10 miles shy of Beaumont. I'm the owner of a Kenwood HD radio and have been nothing but ecstatic about HD radio. On AM, it sounds good but is very unreliable and has an amazingly short range. Radio Disney (WBYU) starts dropping out of HD before reaching LaPlace.