Pete, I don't think you can just add 40% plus 20% and multiply by 540 lines to determine the needed resolution. It just doesn't work that way.
American Cinematographer reviewed the XL1s and did several lens tests with resolution charts etc. They determined that several lenses had superior resolution (the two manual lenses, if I recall correctly). I think it may be safe to say the two manual lenses should be adequate for the XL2. They are what an idie would wnat to use anyway, for the extra control. The 16x stock lens (white lens that came with XL1) is weak on the new chips, hence the new 20X. The 3X wide angle show the limitations of the DV format. Detailed WA shots (landscape) are not very crisp. But it is a fairly well corrected lens and if used close shows suitable resolution on the old chips. Until the new camera ships I'll reserve judgment. Wide angle is particularly troublesome on the DV format. The Leica lens on the DVX shows too much barrel distortion at the wide end when used on interiors (at least my clients say so). I would go so far to say that there isn't a good wide solution on for the DV format, except wide primes on the P + S Technik mini 35.