You can actually get a faster CPU that is more power efficient than the slower and/or older one. CPU speed and core count doesn't necessarily = more power draw. Maybe running full-bore they might, but not always. Just look at an Intel Pentium D versus an i series chip. Vastly superior performance at the same or much, much lower power and heat requirements.
Newer chip generations come with die shrinks, better power gating, more efficient overall designs (higher IPC counts), etc. Not you mention you have Rush To Idle; The faster you can complete a task, the sooner you can drop to a lower power mode.
Just because you don't have fancy graphics doesn't mean you wont, or cant, use a lot of memory or CPU cycles. I'm all for not compromising battery life, but I still wouldn't mind more memory and a more powerful CPU IF they can still rate the device at the same, or better, battery endurance and price.