I really would like to get a robot but somehow I just can't make the numbers / benefits work to replace the Polaris either:
2 hours at 200 Watts vs 2 hours at 1488. And the Dolphin cleans much better. No brainer.
I run my Polaris about 2 hours a day on average (probably more like 90 mins actually, but I'll roll with these numbers): That is 2.6kWh savings per day (2h x 0.2kW vs 2h x 1.5kW). At my electricity rate of 9c/kWh that would save me 23cents per day or $85 per year. Someone check my math.
I am more frugal than most pool owners I'm sure, but I don't think that's 'no brainer' territory yet. That's a 8+ year payback period for a relatively cheap model. For me personally, I think I'd need to be able to get that robot for around $300-400 before I'd buy one to replace the Polaris based on energy savings. Once the Polaris dies and needs to be replaced anyway then it would get more interesting.
I also don't see the big time savings that some here are touting. The old Polaris does a decent job and gets the floors quite clean except for one of the far corners in my pool that it doesn't reach too well, but I can just brush that debris to the center of the pool in a matter of seconds every couple of days. I almost feel like a TFP heretic to say this, but I only manually vacuum around 3-4 times per year and the
pool is basically always very clean and clear (except right after a major storm). I have to brush obviously, but doing that 1-2 times per week doesn't take but 5-10 mins either.
Don't get me wrong, I'm not a Polaris fanboy and I'd probably pick a robot if I was starting from zero. But so far I cannot justify getting one to replace my working Polaris, as much as I'd like to because I like cool tech toys.