Hi Mort, and welcome to the Asylum.
Think you may posted up a similar question 'elsewhere,' so this may just be a repeat of what you've already read. Rod choice is dependent on three major things. (Yes, yes, there are others too.) Size of and flow rate of the water, size of the fish you expect, and the size of the fly you want to chuck. Is a 6 or 7 too light for normal Steelhead fishing? Not in the least ... save for you're on the Skagit or Thompson (well, BIG WATER). There you need a rod with lots of 'umph.'
Normal flows, etc., you'll find that a 6wt is fine for lower water work (summer/fall) and you'll need to 'bump it up a bit' come winter/spring. With that in mind .... you can only go with one new rod ... take a 7. You can handle one hell of a fish on a 7wt 2hander.
Simi rule of the thumb is a given weight on a two hander is (roughly) two line weights over the same number in a 1hander. And by looking at the grain weights used to load one vs the other, that appears to have merit in most cases.
Fred