Cool thanks. My interpretation is under 50 MHz that I'm interested in, it doesn't matter. At some high enough frequency, the termination method makes a difference and being hardcore and wanting PFC on a probe or scope's parasitic capacitance, maybe you got to DIY. If we say 1 GHz has a 30cm wavelength, a 3cm or so extension on the T splitter is enough to generate reflections and we might wonder how close to 50 ohms the resistor really is.