For strength in a UJ, the Chinook europin. There is no other

The cup and pin are machined from one piece of billet alloy (no more snapped pins), the bolts thru are thicker (no more rounded off piddly little allen key or phillips head bolts when changing tendons).
See last thread about cup vs. europin.... or look at a Chinook europin in the flesh and u will see what I mean.
I reckon the Chinook alloy RDM extn is good too, the wall thickness seems better then many. I would not worry about extra weight in an extension as it does not affect swing weight of the rig like a boom or heavy sail does for example, and an extra 100 - 200g over a carbon extn is not felt - having a wee before sailing has greater effect.