This is a very easy question to answer. Sylvania sealed beams -- all of them, including the XtraVision -- are garbage. Very poorly focused, low overall output. You may get the subjective impression of "good" lighting, but in (objective) fact your ability to see what you need to see is very poor. Same goes for all of the Wagner sealed beams. Really, the only sealed beams worth buying are the GE Night Hawks. They are more trouble to get (amazon.com is the easiest/cheapest source) but if you are sticking with sealed beams, they really are the only smart choice. Remember, subjective impressions of headlamp performance are useless because they are almost invariably way out of line with the actual, real performance. The human eye is a lousy judge of its own performance -- I include this information to make it clear I am not trying to slam you, Thor; I am sure you really do feel like you have improved seeing with the Xtravisions. That's what they were designed to do, create the sensation of better lighting. It's not real.
And Sylvania's "best" (i.e., most expensive), the Silver Star units, are even worse than the Xtravisions in objective safety performance terms. Total scam; that's what Sylvania mostly specializes in these days.
