Ignore the "SDS100 is harder to program" hype. That's not correct. Basic programming for the SDS100 is exactly the same for the SDS100 and the 436HP or 536HP. If someone sent you a programming file for a 436HP, you could load that into an SDS100 just as well.
There is a learning curve for any of the new scanners, both Uniden & Whistler. But there is a lot of help available here on RadioReference, as well as a number of 'how-to' Youtube videos. You may be 66, but I've got a couple of years on you.
With either the 436HP or SDS100, you can update the main database using the Sentinel software, provided at no additional cost by Uniden. A download link can be found on this
page. Once you do that, scanning can be as simple as entering your
location, a range, and selecting the Service types of transmissions you want to hear. Then start scanning. As you get more comfortable with the scanner, you can tailor your Favorites lists to focus your listening on areas and agencies of interest.