Dueling experts

[Brion Toss]

Hi,
The biggest problem with using the spare main halyard as a topping lift is that, when you need to use it as a spare halyard (skyed or broken the primary; want to set the trys'l before lowering the mains'l), you no longer have a topping lift. In addition, you are working at a mechanical disadvantage, rather than the 2:1, 3:1, or more that you can get with a tackle at the end of the boom.
Take that tackle to a Spectra pendant, and you have a stronger, lighter, softer, corrosion-proof pendant, not that wire thing.
Take the hauling part inside the boom to a belay at the gooseneck, and it's easy to get to.
Make the pendant whatever length you want, to allow for as much boom topping as you are likely to need. If you need to take it higher, you still have that spare main halyard.
A rigid vang can be installed instead of the topping lift. And again,the spare halyard is backup most of the time, but available if you need it.
Finally, you can engineer lazyjacks so that they can function as last-ditch quarter-lifts. This support-in-depth can be quite attractive on boats with very large, heavy booms and no place for a rigid vang, like big catamarans, and monohulls with minimum boom height above deck or other issues.
Fair leads,
Brion Toss