Here is my opinion on the matter, though take into account that recently I have not played as much lancer, more 1h cav.
An experienced lancer can outreach a 2h sword stab, but only in ideal circumstances and with maximum skill. Since the 40° change, this being so difficult that I would not think anyone but the top 3 lancers on EU and them only when on their best could reliable hit a staby 2her. Despite having a lot of experience as cav myself, ever since the change I did not attempt 2hers in such situations albeit because I was not playing lancer all the time - maybe if I was I would have.
This however, I think is a problem, since a 2her is the ultimate melee weapon and it has anti cav cabalities which are at worst decent and at best deadly. A single stab is usually a horse kill and this means 90% of the time the rider dies before even standing up. Now, if this were a pike or spear this would be expected in terms of danger to horses - but pikes and spears have serious drawbacks in other fights while the 2her is supreme in them.
And another issue is that a decent swordsman can use the stab anti cav with great effect while it takes maximum experience to even try to lance him, and horsemen shouldnt (and most longer living ones - DONT) even attempt so. Also we should consider that an aware swordman is not in danger of a lance, even if it wouldnt have the ability to own him, due to down block and jumping aside.
So in conclusion, even though theoreticaly the lance beats the 2h sword, in practice I would say that 2her anti cav potential is too high and would almost always bet on a 2her stabing over a lancer (1on1).
p.s.
also the last Kafein's post is right, and a good lancer must adjust so that he strikes with perfect range on assumption to 2her will move TOWARDS him, else if you do not do it assuming foward jump and movment AND the swordman does - he kills the horse first. BUT this means that 3 of 4 times the 2her moves away or sideways, causing a miss for both. So a lancer doing it perfectly still has only 3/4 chance to hit.