As I've mentioned in years past, its sad that directv pretends to not have a receiver database model that lets them determine what receiver a customer will receive, because they have that exact database.
They know what you have on your account in the database, yes.
As far as what a customer is going to get, you really don't understand how it works.
Far more than 90% of receivers get to customers via a tech. When you schedule an install or upgrade, DirecTV has no idea what tech will be doing your install, much less exactly what equipment that tech will have on-hand that day.
Example: It's Jan 1, and you order a new install. Your install is set up for Jan 6. How can you expect DirecTV to know what equipment some random tech is going to have 5 days from your order date? Oh, but then, something comes up, and you've got to go out of town, and now you're going to reschedule for the 15th. Whatever inventory might have been available on the 6th is not necessarily available on the 15th.
A local DirecTV warehouse doesn't get to order receivers by model; they only order by receiver type. And very often, they don't get as many as they ask for, especially when inventories are low. So, it is very common for a warehouse to look at their volume for the next week and order, say, 3,000 HD-DVRs. What arrives a few days later? 1800 refurb HR21s and 300 HR24s. Typically, then, several of the field supervisors load up their vans with HR24s to dole out for calls that they feel "really need them". So, 100 HR24s are set aside that way, and 200 are left to be randomly distributed to the techs that week.
The next day, nearly all HR24s issued to techs are likely going to have been installed. The rest of the week, everything installed is going to be an HR21, at least until the DECAs run out, and then techs will have to beg their supervisors for an HR24.
Keep in mind, too, that many of the installers are subcontractors. A sub may have, say, 10 installers, but all equipment is checked out to the one subcontractor, and DirecTV has no information on which installer for that sub has what equipment.
So, given all that, DirecTV has little interest in promising any particular model number. It would result in tons of reschedules and cancelations because of people waiting for their model number to be available, as well as a bunch of receivers piling up that no one wanted while jobs waited on hold for "the new hotness" to be available.
That isn't gonna happen.
Even if you argued that DirecTV has much better control of the receivers they ship out directly (and they do), the same basic thing applies: everyone would want the latest receiver. That would defeat one of the benefits of the lease model for DirecTV, and that isn't in their best interest.
So, we're back to this: there is already a solution for those folks who want what they want, and that is DirecTV retailers. If you must have a specific model, there are retailers at your disposal to help you.
If you are trying to get a "deal" by working directly with DirecTV, who can undercut the deals that retailers can offer, fine, but know up-front that you're going to get whatever model you get, and aren't going to have control over that.
You can't have it both ways.