I've never flown controline with Spectra but I've tied thousands of knots with it on the boat.
A few things we've learned:
Never cut it with knives or scissors. Get one of the hot cutters they sell at good tackle stores.
Without a doubt, for tying directly the best knot far and away is the palomar knot.
When we tie directly, we never trust the knot on it's own, we glue it.
Chuck
(BTW, if you fish offshore and want to attach a leader we find the FG knot works the best and it's profle is nice in that if you use a wind-on leader it will go through the guides.)