Rich McVeigh is the line maven. He ran through a bunch of stuff before he settled on VT-100 (I think). It's one of the stiffer lines, and NER recommends an 8:1 sheave/diameter, so theoretically, you need a 40 mm sheave on the halyard, which is pretty big.
Running over a smaller sheave won't initially compromise the strength, but you'd need to keep an eye on it and end-for-end it when it starts looking tired.
I've got what came on my boat (a 2007), which is similar to Samson Amsteel - it's a Dyneema single-braid. It works well enough. Heavy air is the only place you're going to notice a difference, and there, a bit of stretch make help you by de-powering the main. The trick is to make sure you're always powered up enough through the lulls.
Kind of like a DN iceboat's mast flexes obscenely to absorb and power through the gusts.