Barton size 6 plain bearing on the mizzen, size 7 plain bearing on the main, both with 10mm halyards. The main only has size 7 because the halyard was originally 12mm.
You might do well with those combination ball/plain bearing blocks, Gary, so long as you heed the advice to go oversized. Your halyard loads will be somewhat less than mine and Gary King's. I'm only saying that it's at best a partial answer to the halyard block question - there will be some benefit, but not when it's most needed. The full answer, unfortunately, comes with a high price tag. Sometime, I'm going to have to bite the bullet, because I'm not getting younger and the sails aren't getting lighter.

Gary Pick wrote:

Gary King wrote:

Gary Pick wrote:I've just come across these.

http://www.bartonmarine.com/products-size-3-blocks.asp
A ball bearing double sheave block maximum rope 10mm for around $AU45 + GST.

Gary, is there a price list for those blocks somewhere?

Gary have a chat with this bloke, he contacted me in response to a thread I started on BB blocks on the WBF. He stocks them here in Oz.
andrew@denmanmarine.com.au

Almost all my blocks are by Barton, being from the UK. I recommend size 2 for such things as sheet spans, sizes 3 and 4 for sheets and halyards on inshore boats, sizes 5 to 7 on sheets and halyards on offshore boats. Note Arne's comments on using oversize blocks, and use size 4 5 or 6 for a 10mm halyard. Barton ball bearing blocks are not suitable for halyards, but are suitable for sheets.

Gary Pick wrote:I've just come across these.

http://www.bartonmarine.com/products-size-3-blocks.asp
A ball bearing double sheave block maximum rope 10mm for around $AU45 + GST.

Gary, is there a price list for those blocks somewhere?

Gary King wrote:What about these Ronstan Core blocks?  (USD 76.45)

They have some funny 2 stage bearing system, roller to plain, would they do the trick?

Harken have a similar model, called ESP, with the same feature - ball bearings take the low loads, but when they deform a bit under increasing load, a plain bearing takes over.. My view is that they will work very well for sheets, but not so well for junk rig halyards. A bermudan halyard is typically under little load all the way up, as the sail is hoisted, and then is under much more load, with little movement, when the luff is finally tensioned. That is the use that these blocks are designed for, and they will do it well. A junk rig halyard is typically under increasing load all the way up, as the sail is hoisted, not only right at the end. Thus, just when you need the block to be free running, as you hoist the last two panels, it starts to act, not as a ball bearing block, but as a plain bearing block, which is not what we are looking for. So yes, the system will  help a bit, and will have a longer life than a pure ball bearing block, but it's not the complete answer for junk rig halyards.

I was looking at some double sheave ball bearing blocks recently, Ronstan I think and they were $AU200+ each. They would be nice though. I plan to use a 4:1 system for my halyard on a sail a bit over 30 sq Metres.