The wattage controls the rate of the transfer, not the peak temp. A lower wattage oven may reach 700F, but it will take a lot longer to get there and it will take a while to recover after a bake. If you look at the spec sheet on the link, you'll see that the lower wattage oven takes 60 minutes to reach 500, while the higher wattage version takes 15 minutes. 1800 watts is basically a hair dryer, btw.
After perusing the spec sheet, though, the wattage should be the least of your concerns. Remember talking about stone thickness? These stones are like tissue paper. A 1/4" stone is worthless.
Another thing I noticed was the thermostat controller. This has one single thermostat controller. You need two independent controllers- one for the top element, one for the bottom.
Based on this spec sheet, I can now give you my opinion on Nemko. Nemko is equally as crappy as Baker's Pride- which, honestly, doesn't surprise me, since the countertop market, as discussed previously, is so rife with dishonesty and fraud.
Paul, what do you need this oven for? Is this for personal or professional use? What style of pizza are you hoping to make? At the end of the day, I think a conventional home oven with a good stone will make pizzas better than any of these non-Sage countertops.
Edit: Btw, drop DNA Dan a PM- perhaps he has a more direct email for the Sage re-seller.