Paul from R&S is active (very knowledgable technically) and has provided some very useful information as shown here for example, note video author.
https://www.eevblog.com/forum/testgear/comparison-between-siglent-sdg1000x-and-2000x/75/Keysight used to have a representative that participated here, but haven't seen anything recently, and we haven't had a need for contacting them, so no reference here.
So far not impressed with GW Instek, alto only a single issue/request, no big deal.
Rob is active as we all know, and extremely helpful for folks with Siglent gear. Siglent NA has also been helpful for our needs/request, as are some of the other folks involved with Siglent gear. Overall very impressed with Siglent support here, and from NA.
There is so much useful and important information flowing here on Siglent gear, of course you need to filter the responses/claims/non-sense/bashers/fanboys/info sources and such, but once you've developed your select "filters", one can glean a tremendous amount of highly useful information on instrument usages, features (some hidden), upgrades (hacks), limitations, repairs, and so on.
For example, just today over on the thread about the AWGs and the note about the little known SDG2000X & SDG6000X feature to "tune" the Reference Oscillator. Highly useful, but little discussed feature (wish their DSOs had this!!).
This site alone is probably Siglent's best advertising resource, at least for the smaller customers, which they seem to care about and support after the sale.
Of course YMMV.
Best,