They have potential?
Most people believed that they were sourcing primarily from "Merck" although their catalog offers things Merck did not so it would seem they have multiple sources. When Merck got shut down, Ronsen also shut down for a week or so and when they returned their price list was quite different as to what was and was not available. Part of the changes also seem to be a result of removing items that were causing other suppliers problems with the Chinese govt and their rep Andy has apparently said as much to a number of customers.
Unlike most resellers they appear to order custom for their own inventory (much like the larger domestic vendors) instead of just reselling whatever the finishers have available. There were a few examples where concurrent Merck and Ronsen orders for the same product produced similar but not identical products in terms of cap/crimp colors, test results, etc. which tends to support that theory.
Their testing prior to the brief shutdown has been "decent". Nothing spectacular, but nothing terrible with the exception of one instance where a test donor ordered semaglutide but was sent semax instead (not sure if/how that was resolved). Most are under 10% +/- in fill and purity is consistently in the low-to-mid 99.x% range. There are still a handful of tests pending public release, but unfortunately they're all from the pre-Merck shutdown time frame as well so really until newer tests get done it's hard to say if the results will be comparable or not.
FWIW since opening back up there has been an increase in complaints regarding comms and customer service.
From an email I sent them a couple of months ago they prefer bank transfer or BTC payment but were at that time accepting PayPal sent as F&F. They do not use Alibaba.
Bottom line is they're probably reasonably safe to try, but probably worth waiting for more recent test results if possible. From what I've read it does seem like their main rep Andy and his assistants are far less patronizing and pushy than some of the other suppliers so that alone gives them a slight advantage imho.
Attached is a price list I was able to dig up on Discord from 11-July. Only the items highlighted in gray are currently available.