FWIW, I spent a weekend on the South Llano river here in Texas a couple of weeks ago throwing #6 cone head buggers with a 4 weight TFO TiCr, which is fairly stout for a 4 weight, and it wasn't a bit of fun from a casting standpoint. On the other hand I've thrown the same fly with a 5 weight TiCr all day with no problem. Decide what you want to fish for and how you want to fish and decide from there. Having said all this my 4 weight TiCr is probably my favorite rod and I will continue to use it when appropriate, I just learned throwing #6 cone head buggers is not it's strong suit.