Is there a noticeable difference between the two and if so how much difference dose it make? TIA. 
@Trebor‌ Primary noticeable difference is that 800W does not interfere with other kitchen appliances, whereas we had customers noticing some interference when using our 1000W unit.
@Trebor‌
Oops. @Trebor‌ I can’t speak to how capable the 1000w was, but I find the 800w underpowered when cooking vegetables (which need to be cooked at higher temps, like 90c). It can take a LONG time to go from 80 - 90 (if it even gets up there) and a LONG time to recover after putting in the veggies.
Oddly, this feels inconsistent… but this seems like a very unlikely bug.
@jshannon Using a smaller pot should help with this as there is less water for the Precision Cooker to circulate through. Also, I find it useful to have the veggies out on the counter while heating up the water and making other meal preparations so they have a bit of time to warm up to room temp. It seems small but it does help a little bit with avoiding a longer temp recovery 
Thanks for all the advice.
I’ve used my 800w unit in 2- and 3-gallon Dutch ovens and stock pots with no additional insulation. It takes the Anova PC about 27 minutes to heat 2 gallons of 52°F tap water to 135°F. The cooker has no problem keeping the water at temp. If I’m going to do veggies at higher temps like 183°F, I put the whole thing on my induction burner and heat the water using both the burner and the Anova PC until reaching the desired temp, then shut off the burner. It takes about 8 minutes. Again, the Anova maintains the higher temps without difficulty. So for my uses to date, 800w is working well for me.