Realistically @brimar the DTR2100 was launched according to reviews of the time c Feb 2014 so it is over 10 years old from launch. Typically PVR type functionality (eg viewing aerial channels/recording them) tend to continue to work well and PSB players are maintained to provide at least basic level of catchup/ondemand of their PSB content.
Commercial subscription apps tend to have to continue to develop & compete by adding more features and content so eventually there will come a point where they would struggle to run as effectively on older tech boxes compared with more recent tech.
So i would expect you get a better level of performance than you are experiencing if you did move from the T2100 assuming that your issues are not being caused by a broadband problem.
The main issue with the PRO box currently not having the latest functionality is I understand related to an upgrade to its drivers being needed to allow Amazon to update the Prime app to include its FAST channels. (there is also a bit of a two tiered functionality depending upon hardware as to whether the Amazon app has Rewind, pause and fast forward available on its own live sports streams).
