When iRobot Corporation (IRBT 0.58%) unveiled the new Roomba 870 on Friday, I took a quick glance at a few of my favorite deal sites and forums to see what consumers were saying.

Curiously, most immediate responses seemed to share one common theme: confusion.

iRobot's new Roomba 870 retails for $599. Source: iRobot.

Apart from a slightly different color scheme, it's admittedly difficult to tell the difference between the new $599 bot and iRobot's four-month-old $699 Roomba 880.

Both are available exclusively on iRobot's website, both have the improved XLife battery, both have larger debris bins, and both feature iRobot's new brushless, maintenance-free "AeroForce" cleaning system, which is arguably the most significant upgrade since Roomba vacuums were first introduced more than 11 years ago.

So what is the difference? With the 880, the extra $100 gets you a remote control and the ability to "clean room-to-room" with iRobot's Virtual Wall Lighthouses. But if you don't mind skipping the remote and sticking with a couple traditional virtual walls -- which simply block your Roomba from entering any given area -- the 870 will do the trick while offering all the biggest core upgrades.

iRobot knows what it's doing
It might seem silly at first to make these simple distinctions, but iRobot is demonstrating a certain level of predictable brilliance here.

First, iRobot knew even with the steep price tag, early adopters of its new brushless bots would happily gobble up the 880 over the first few months. Sure enough, during last quarter's earnings conference call, CEO Colin Angle told investors sales of the 880 "have exceeded those of all other new products over the same time frame."

What's more, keep in mind the Roomba 800 series robots have yet to expand to other retail outlets. When that happens, it's not unreasonable to expect iRobot's sales to accelerate even more.

In the meantime, and now that early adopters have had their fill, the 870 should help iRobot grab more value-conscious consumers who still want the powerful new AeroForce system but don't need all the bells and whistles. I'm part of this group, and have to admit Friday's announcement has me not-so-secretly wishing my old Roomba 650 -- which still works fine, mind you -- will kick the bucket and give me an excuse to upgrade.

But that's not to say iRobot's older brush-based models don't have their place. Angle also told investors last month that robotic vacuums now represent around 15% of all vacuum cleaner sales. In case you're wondering how much more market share they can take, he says that's comparable to the rate of adoption achieved by both microwave ovens and dishwashers at the same stage in their respective life cycles.

Foolish takeaway
iRobot is currently calling for 2014 home robot sales to comprise 90% of total revenue after growing 17% to 20% over last year.  However, given iRobot's history of underpromising and overdelivering, I wouldn't be surprised if the Roomba 870 plants just the seed iRobot needs to once again beat expectations in the coming year.