I have a lot of Techs, quite possibly one of every variant, and there are two that I return to again and again ... the slotted British from the 1940s and the brass with bakelite handled American from the 1950s. There's also the "raised flat bottom" which I seem to reserve for a special shave and it never really turns out quite as well as the regular slotted British Tech.
To return to the original question, if you've shaved with the slotted British Tech, the 'New' is not going to feel that dissimilar. I know, I l know, the 'New' has teeth and "is more aggressive" but I think some of that is in the mind. I use mine when I've a week or so to mow down, but in practical fact the slotted British Tech would get through it with little problem.
I like the 'New' and if I'd have asked the same question (which I probably did some years ago), I know I would have to get one in ... Yeah, you need one in you life!
While on Techs, I wonder if anyone has seen one of these. I cannot find another example anywhere ...