I know that sealed bearings require less maintenance then cup and cone loose bearings. However, since I do have the tools to maintain loose bearing hubs, should my next wheelset have sealed bearings or loose bearings? Is there any difference in performance between properly maintained loose bearings and good quality sealed bearings?

Loose ball will always own cartridge bearings when properly adjusted - but the difference only really matters if you're racing.

If you're going to be doing all weather, around the year rides in crap conditions - do yourself a favour and **** the loose ball hubs. e.g commuting.

There are theoretical benefits to loose bearing hubs but the advantages are minor and have been debated endlessly. Shimano uses loose bearings in all of their hubs, including Dura Ace. Campy uses loose bearings in their high end hubs and is starting to use cartridge bearings in their lower lines if that means anything.

I have both cartridge and loose bearing hubs. Cartridge bearings are virturally no maintenance and over the past 3-1/2 years on a mountain wheelset, I have zero issues with them. However, I love to wrench on my bikes and do miss the opportunity to sevice and adjust loose ball bearings. For some reason, knowing I packed the hubs and adjusted them just right, completes my entire riding experience. Yes, I am partial to the loose ball bearings.

You and me both. I really love to get the loose ball hubs just right. I get great satisfaction in the feeling of bearing play disappearing completely as I'm 1/3 rd from completely closing the QR

That said, I've run cup/cone bearings for 5000 km without any maintenance, and the hubs looked like new.

Well, technically this isn't correct. Don't forget about the Dura Ace wheelsets and higher end Campy hubs we discussed not long ago that have the flexible, plastic bearing retainers. So these would be cup and cone, but not "loose."

To the OP, the term should really be "cartridge" bearings, not "sealed" bearings. Lots of cup and cone bearings are considered "sealed" (although some are better than others). I've got old hubs that are actually labeled "sealed bearing hubs" and they're simply cup and cone hubs with seals. Shimano's mtb hubs, which are of course cup and cone, are from my experience sealed very, very well-

Difference duly noted but PLEASE, let's not open that topic again.

Agreed.

Thanks everyone!!