38 is the smallest you can go on a standard 130BCD. So you may as well get a matched Shimano or FSA 39-50 or 39-52 for a triple. I found the 26 to 39 to be a huge jump and the 28 works smoother.

I've tried a generic granny from Tandems East and TA rings from Harris Cyclery. They all needed to be spaced out differently than Shimano or FSA so be prepared to experiment with chainring spacers.

Warning-the new Flight Deck is expensive. The OP didn't specify if he wants to use one. The older computer works with shifters 7803, 6603, 5603 and older. I think the OP could continue to use an existing harness with a new (last generation) 10 speed computer.