The air block held up fine over the weekend but on the suggestion of a few pros and the guys here I've elected to replace it prior to going mast up again. I looked at the Harken T2 and it's construction is lighter and less tough than the air block. The 22mm micro is a good choice but sized for 5mm line, and I have a halyard cover that is a tad thicker so the friction might be higher than I'd like. Plus metal banging on the metal mast may not be so ideal, though I have teflon tape in that area.
Hence, the choice was between the Karver KBO4 at $70 (ouch), this classic Harken block:
http://www.harken.com/productdetail.aspx?id=5627&taxid=424or this Ronstan block:
http://www.ronstan.us/marine5/product.asp?ProdNo=RF35101DI went with the Ronstan since its what others use, has a higher SWL than the Air Block, and weighs 0.3oz less than the classic Harken block plus contains no metal
