Cleaning won't take any longer for the thermowell. Between brews I clean then soak my BB bit's in Starsan before reassembly (I have the original buckets without thermowell), so can't see this adding much extra effort.
I assume the Brewmaster bucket comes with the digital temp sensor and thermowell? If so, there's nothing stopping you from using your STC probe insulated on the outside and compare it with the digital reading of the probe. Consider it research for the rest of us.
Then, when you buy a second, you could compare differences between the two fermentors in the same ferment chamber. Further research!
Being a static fitting I can't really see it leaking and for an extra $50(?) you probably couldn't make a clean hole and fit a thermowell in it for that much cheaper.
I guess the main decision is whether it's within the budget, otherwise you can't lose either way, they're both nice bits of kit. Would I have bought the Brewmaster over the original series? Maybe, maybe not, but I have all the tools at my disposal to modify one if I wanted too.
Whatever you choose, do me a favour and email this Andrew at Full Pint character several times, constantly changing your order and asking ludicrous questions whilst making extravagant demands. Do it. Test his mettle.
(No affiliation with Full Pint aside from meeting the boys via this site and it's consequent gatherings, as well as a general love of brewing and the odd naked brew session.)