It is likely all three variants will have the same CODLOG setup with the MT30 GT for high speed operation and MTU diesels generating electricity for the slow speed electric motors. The MT30 has been rated between 36 and 40 MW or approximately 48-54,000 hp. Most specs I have seen place the T26 at 7,000-8,000 tons. I don't know the waterline length for a T26 but LOA is 149 meters (wiki, sorry) which is 488 feet. Assuming a 450 foot LWL, the maximum hull speed would be 29.7 knots. For 8,000 tons, you need approximately 40,000 hp, for 9,000 tons, 45,000 hp would be required. Hull shaping and the actual LWL will change these numbers somewhat. In any event, the T26 should have enough power to get up to around 30 knots which is where the RCN would like to be.
Unlike the Zumwalt, QE class and T45, IEP was not considered partly due to cost but more likely due to the problems with the T45's propulsion system. Too bad, IEP is the future and has both the diesels and GT generating electricity for electric motors and hotel load.