Requests although I see them = nothing
Often your call will come much after the installer leaves the warehouse and even if it comes before, many of them get what they get.
If I say my customer wants an HR24, do you think my warehouse guy cares? Nope.
If you want to guarantee a 24 series then go to a retailer.
You may pay them or lose certain promotions but you will have 24's
All receivers are fully capable of delivering proper service, it just depends on what is important to you.
That being said, most D* orders currently are getting 24's but you choose to roll the dice.