I recently bought a 34g Solana cube with a 20" 250W Sunpod. I just started a chronicle thread for this tank:
34 gal. Solana cube by kapu
The tank is open, and my only cooling is a back-mounted fan on a temp controller. Heat is no problem so far, though it is still pretty cool here in the Pacific NW. We will see how things go during our 6 wk. summer that starts in about 3 weeks. No AC here. Evaporative cooling really does work if you get enough air flow across the tank surface.
Beyond intensity, one big advantage of the 250W Sunpod over the 150W is it has a remote ballast for heat reduction. The light canopy still has a cooling fan of it's own. If you can run an open tank, I think the Sunpod is a great option. It does come with a hanging kit if you want to move it higher above your tank than the 4" mounting legs.