While I don't pretend to understand what NXDM is, should I buy a 436, would I not be able to purchase and self install the upgrade?
It's NXDN, not NXDM.
NXDN is a different type of emission code instead of P25 (digital, but a different form of digital than NXDN).
If you buy a 436HP (or 536HP), right now, you have the option to get the NXDN upgrade for $30 instead of the 'regular' price of $60, which will go into effect once the Sentinel software is updated. The basic question is whether or not there are any NXDN systems in your area (Harris County) that interest you. Looking at the list of trunked systems in Harris, I only see a few systems in the county using the NXDN format. A couple of business systems, and a couple of school districts. Likely, there are more, at least business users, but they have not been identified & added to the database. Whether any of the current systems, or potential new (yet to be documented, or maybe only in the planning stage right now) ones might be something of interest, you'll have to consider the options. You can always add it later, should a NXDN system that
does interest you come into play at some future date. It would just cost you $60 instead of $30, if you wait too long. I have two NXDN public safety systems here in the DFW Metro area, so NXDN was a good update for me, especially at the discounted fee.
Unless you have severe simulcast issues at your specific location, there is likely not going to be such a large difference in capabilities between a properly programmed 436HP versus the yet to be released SDS100.
The 436 will basically be obsolete in a few months when the new SDS100 comes out (just read the other posts on here). Honestly if you're in the market for a new scanner I would just wait a little while longer. There are issues with the 436 (mostly related to simulcast) that should be improved when the new scanner comes out. Even if your area doesn't have a simulcast system currently, there is always the possibility they could have one in the future. If you're going to spend all that money you want to "future proof" your investment.
If you always want to wait until a new, unreleased, product with improvements in form and function comes out, then you'll never actually buy a scanner. Uniden is working on the final changes and adjustments before the SDS100 hits the market. But, as UPMan has said before, they are always working on something. At some future date, whether a couple years, or some other time frame, Uniden likely will have a new product that does things the SDS100 cannot. Whistler has also hinted that they may release something around May. What they have up their sleeve, I have no idea, but if they plan to compete in the scanner market, they also are likely working on something farther out in the future than this coming May. There is no way to totally and finally 'future proof' your scanner choice. At some point, something else, eventually, will be released.
