I bought a Philips HQ8150 when I discovered that the cost of buying replacement heads for my old HQ7830 wasn't too different from buying an entirely new shaver. I think the cost of buying replacement heads was about £35, so, half the cost of a brand new shaver with brand new heads. Sounded like a good idea to me.
Philips sell a million different designs and models of rechargeable shavers, which can get very confusing when you're looking to buy a new one. Their product range is evidently not designed to be simple and user-friendly. Anyway, after months of research and analysis I deduced that the only benefits of the £140 models over the HQ8150 were the addition of some blinking lights, LCD displays, and bulky automated cleaning stations. The HQ8150 seemed to be pretty much the same in terms of the actual shaving heads.
So how is the HQ8150 to use? Well, I must admit, compared to my old HQ7830 the motor sounds a little under powered and seems like it's continually running out of charge. But maybe these newer shavers just use quieter or slower motors than the older models? Who knows. The HQ8150 seems to be optimised for getting rid of stubble as it does a worse job than the HQ7830 at getting rid of longer hairs. If you have a week's growth of beard, you can quite happily glide the HQ8150 over your face as it fails to cut the majority of hairs, which is weird, given the plethora of blades spinning around.
However, once the HQ8150 does engage with the hairs on your face, it does a great job. It enables you to get a glass smooth shave, and go over the same area again and again, without aggravating your skin and causing it to glow red. Cutting yourself is almost impossible, which is great news if you've had bad experiences with wet shaving.