Review (5/5): What you *really* need to know!!!
When you buy a Norelco shaver, the shave is determined by the first digit of the model number. There's the 6xxx series, the 7xxx series, the 8xxx series, and, now, the 9xxx series. With rare exception, all models with the same the first digit in their model number use the same style of shaving heads. Within a series, you get more features as the model number gets greater (from corded to cordless to quick charge with more metering), but the shave within a series is pretty much the same.
Check each shaver's cutters, either by blowing up the picture of the shaver or by blowing up the picture of the replacement heads. The 6xxx series, like those before it, has heads with slots across the entire cutter. With later series, part of the cutter cover contains small holes rather than slots.
When my 5xxx shaver started to lose its ability to hold a charge, I decided to get "the best" and bought a 9xxx shaver. I knew that it sometimes took a few weeks for new heads to seat themselves and give an optimal shave. However, even after this break-in period, I found myself leaving the 9xxx on the dresser and grabbing the 5xxx for a much more reliable shave. This is what prompted me to take a close look at the heads and comapare them.
I can't imagine Norelco made the change to their cutter covers without extensive market testing. When I called Norelco Customer Service to tell them of my disappointment, they had me return the 9xxx for a full refund and told me that I'm not the only one who doesn't like the new heads. They also pointed out that the 6xxx series heads are the same style as the 5xxx heads.
I agree with what others say about the construction of the 6xxx shavers. However, lighter plastic casing is not always bad, as personal computers have demonstrated. More important is that the 6863XL gives me the same good shave I came to rely on from my 5xxx shaver.