A longer ETT that doesn't give you the desired frame reach only helps if you can live with more saddle setback. Power and desired weight distribution will determine your saddle setback, so unless it was wrong before, a longer ETT that doesn't give you more reach doesn't help.

The best thing to do is figure out your desired bar height and reach (both relative to the BB). Then for each frame you can calculate what you'll need in terms of spacers and stem length to achieve that. A tool like the free version of www.bikecad.ca | Bicycle Design Software will save you a bunch of trig once you get past the learning curve.