I read the Gartner report and RIM BlackBerry BES is still the best available, but there are concerns that TCL could weaken the package.
The concern is that TCL BlackBerry are Chinese owned, and companies ruled by Chinese laws are difficult to trust.
China has a very different set of customs, ambiguous laws, and inconsistently enforced regulations. Chinese companies are very dependent on political backing. Would you want your business data being intercepted at the handset and copied in China? How can you know that isn't already happening?
One quick glance at the Transparency International is enough to tell you that China is extremely corrupt. https://www.transparency.org/news/fe...ons_index_2017
Corruption raises concerns for security-conscious operations. According to Chinese sources, the official number of Chinese officials 'under supervision' is over 997,000. How many should be under supervision, or dismissed?
According to Forbes, "Foreign investors also have reason to be concerned. Firms in China find that corruption can divert staff time from normal work to satisfying government officials". So there are potentially many Chinese government agents not simply looking for exploits in in TCL handsets, but having tangible influence in hardware selection and configuration.
Fixing the regulatory landscape means opening media, reducing government control, and prosecuting former party members. There is no sign of that happening in China.
For these reasons there are security concerns when using TCL handsets, but there are similar concerns when using Foxconn handsets such as Apple iPhone.
I do not transmit business decisions over any handset because services such as BES cannot fix leaky handsets. But I agree if you just want to set the bar higher than average then BES is about as good as it gets.