I don't know how active this site is. I found it many years ago went MX-500 ->700->850. Wow the 850 lasted for me for a long while. The 850 is worn, and I have bought spares to keep it going. But I wonder what I should do now. Questions-

What model? I am a diy'er

Can I copy the remote profile to migrate to a new remote? Even if I move to a complete control remote.

or should I give up on URC and move to Harmony or get a global control and build the remote from scratch using an iPhone for the remote.
Many thanks.
IS

Using a phone for a primary control device is a bad idea. It always has been, it always will be. You can accomplish some cool things inexpensively on a phone or tablet and apps on those devices make great supplementary control. But there should always be a primary dedicated control interface available for a system.

Being you have been using an MX-850, I'll guess that you are just looking to control a small local system (TV, amp, couple of sources). Meaning not trying to control a whole house, lighting, HVAC, and other home automation systems throughout the house.
So in that case, the Harmony line of remotes should be fine.

If you want to get one of the newer URC Complete Control remotes (MX890, 990, etc.) and do the programming yourself, you will need to make sure where you buy it from will supply the programming software to you. It does not come in the box and URC generally does not give it out to consumers directly. Many places (especially non-authorized discount houses) will not supply the software.
I think there is a way to import parts of the MX-850 programming into the CC software but it has been many years since I had to do that. Being how completely different the layout is going to be, it would probably be best to just start from scratch on the new remote.

Many thanks for taking the time to reply. Good advice.
Thanks again and stay safe all....

MX-850 software is standalone. CCP for newer is never going to import an MX850 config. You will start from scratch.

The 890/990 are like Christmas after an 850!

You can import the codes from the MX-850 (particularly learned codes), but not the layout, so overall it's likely going to be faster just to program everything again from scratch with new database codes, new clean learns, and new hex imports where needed.

The newer URC remotes are much more flexible in how you can program them (mixing and matching multiple database codes in a single device, for example, and more sophisticated macros), and as soon as you figure out the vastly different CCP programming style, ALMOST as fast to program as an MX-850.

Just remember to follow prior advice and ensure that where you buy from will supply you with the software. Any help you need you can find from searching or asking in the forums.