KM,
Not all of my open hand casting experiences have been bad ones. It seems to depend on how crisply they are cast. Sometimes (often) the palm of the hands can have quite a build up of - let's call it flash (metal). Depending on the alloy this can require quite a bit of cutting away, filing to widen the receiver sufficiently to take the wire. The worst offenders for this in my experience is Gripping Beast (a range I adore by the way). I end up effectively drilling them anyway.
I wasn't thinking about spear/lance heads with pennons - that might prove difficult. I was assuming some order of drilling to better seat a preferred wire thickness would always be required.
I failed to mention I think your proposed range fills a gap very nicely and it properly expands the possibilities for the medieval wargamer. Many thanks.