Hi
The Dumborc 350 is quite new, so UK supplies unlikely. Through eBay, mine came in a week. I bought it as I already have a Dumborc radio with 5 or 6 receivers and wanted the adjustability and model memory that the new radio has. Other than that, I’m more than happy with my GT5, as others are happy with the GT3. I think you are right that the NT4 is a higher quality model, though I’ve not held one. The GT5 and Dumborc 350 feel solid in the hand too.
As for receivers, you need units that match the TX protocol of your radio. Dumborc use their version of FHSS, Flysky use AFHDS, AFHDS 2, AFHDS 3 and ANT, depending on which radio in the range you choose. GT5 is AFHDS2, Noble is AFHDS3, as an example.
There is a chart on the Flysky website that shows which TX works with which RX.
That is true for most radio’s, which can be considered as systems, though the Radiolink MT12 uses the EdgeTX operating system and a TX module which is capable of working across different TX protocols, so will work with receivers from different manufacturers. Unless you “need” this functionality, it’s probably overkill for most.
They’re all great when compared to the AM 27MHz and FM 40MHz system used 20 years ago!
The receivers for some of these systems can be quite expensive, so it’s worth checking that out too, if you think you will be expanding your fleet, haha!
Please feel free to keep asking questions, there are lots of knowledgeable people on here whom love to help make having RC models a great experience.
Cheers