I'd suggest buying some tmx and making it work, and it if does, slowly sell off your tech pan.

A step or two up in format will yield grainlessness too. I shoot tmy2 in 4x5 and consider it grainless compared to anything from 35mm. A slow medium format choice would also do well.

The dark look sample image looks like pushed film to me. A shortness of shadow detail and hearty contrast. Some filtration options would also help you get the look in more outdoor conditions as well.