Re: Fast 6 wt or slower 7 wt?
I sure agree that fly rod "fit" is a very personal thing...I suspect that's why there are quite a few companies making rods!
Its too bad fly lines are so darn expensive because, as several have noted above, a change of line can really change the way a rod works for you. For years I used Orvis lines, then a couple years ago a guide turned me on to Sage (made by Rio) Performance Taper II fly lines - I switched every floating line I owned, 2 to 10 wt, over to them. All my rods got better and my casting got better. BUT, Orvis made (mebbe still does) a line that they stated was a half line weight heavier than everybody else's standard line; it is still my go to for bass fishing.
So there's a thought: maybe try a bass or pike taper on that TCX. As Frank noted, you said you were going for a streamer rod; accuracy isn't incredibly critical in most streamer fishing situations.