No offence taken. I'll consider what you said and do some research. But I'm having trouble imagining the conditions where spilling reefed main and a jib is not a better balanced plan than jib alone. Like I said, more research needed.
The difficulty you're having wth sailing on jib alone is probably not
attributable to you, or to your boat. As you can see from the above comments, others are experiencing difficulties with it as well as you, and I don't think it's a reasonable assumption that they are all unskilled.
If you will read all the posts, you'll begin to see a pattern. The people who seem to be able to sail well on the headsail alone talk about sailing on 135% or 150% genoa. The ones who are having difficulty are often talking about using a smaller, partly furled jib.
I found that, when sailing on an overlapping jib alone (about 130% or more), it is much easier to sail on jib alone than with a smaller jib. If you think about the basic function of the mainsail and the jib, it will make sense. Basically, the jib provides forward drive. The mainsail pushes the stern to leeward, which helps keep the boat pointing to windward.
If you are sailing on a smallish jib alone, the problem arises when you tack. During the tack, the boat loses alot of forward momentum. As a result, the keel and rudder lose lift. When that happens, the amount of pressure that is being exerted forward of the boat's center of lateral resistance (CLR) by the jib is pulling the boat's bow to leeward. The keel and rudder are trying to steer the bow to windward, but, because they are creating less lift, they don't have enough power to overcome the jib's pull to leeward. The result is that the bow falls off to leeward.
I'll grant that some boats just behave a little better than others, and boat handling skill can maximize the boat's ability to sail on jib alone, but skill can't change the laws of physics. If you're having difficulty sailing on jib alone, try doing it with a bigger, overlapping jib. When the jib is big enough so that part of it extends aft of the CLR, that part of the jib performs part of the function that would ordinarily be performed by the mainsail. That is, it pushes the stern to leeward, and helps the keel and rudder get the boat to point to windward after a tack.