I bought a Siglent oscilloscope from Telonic in November as a gift for my son. We haven't had any service issues (yet) but I spoke to them by telephone beforehand and they were quite helpful - helpful enough to make me decide to buy from them rather than one of the other possible ways of acquiring these things.
I was quite impressed by the oscilloscope's performance. I am experienced with plenty of test equipment from, for example HP (Agilent / Keysight etc), Tektronix and LeCroy and they are generally very good (of course), However, I honestly can't see why you would spend double or more on the same capability when stuff like Siglent is available at a much lower cost. I don't have any experience of Siglent spectrum analysers but Chris G3WIE gave a talk at my radio club recently and he brought along his Siglent spectrum analyser. He seemed happy enough with it and it appeared to do its job perfectly adequately (which, in this case, was looking at spurs from a 4m transverter).
If you are comparing buying new from Siglent or used from, say, HP or Tek I would say that the new equipment has the advantages of being much smaller and lighter, a nicer screen and can easily generate data and screen shots. Not to mention warranty, serviceability etc. I have bought a fair amount of used equipment in the past to avoid the very high costs of new test equipment, but these days you would have to think quite hard about these lower cost offerings, unless you really need top end performance.
Hope this helps.
Good luck with your