I have had mine for 6 years. The only downside, if you want to call it one, is that you have to pay extra for NXDN, DMR. and Pro Voice upgrades. Mine has been on for the most part 24/7 with no problems except the clock and Uniden fixed it and I understand all new ones do not have that issue.
I've had mine first 536 for 6 years and my other 2 536's for 5 years. They have all the options and they stay on 24/7. You would not go wrong with an SDS model either. I don't own a SDS200 but own 2 SDS100's and very happy with them. SDS models are the only scanners that can defeat simulcast if that is a concern in your area.
My 536 works well. I use it in a simulcast area, so I've relegated it to non-simulcast systems for listening and it has had no problems. DMR was pretty much a necessity, NXDN an okay option, and Pro Voice isn't used by anyone of note in my State and I won't buy it.
I personally will vouch for the 536. Mine has been on 24/7 the first 3 years of its life, no issues. the last 2 or 3 years it has been in a dirty dusty dump truck. It's still hummed along. Still rocking the original micro SD card (Yes I made a backup).
It is a late 90's dump truck that doesn't keep the dust and dirt out very well. a couple times a week the cab and scanner gets blowed out. This fall I will pull it out and pop the top and clean the inside. But I will say, I am very impressed.