Many XLT bikes with freakishly tall seattubes have top tubes that are only max of around 61-62cm, quite short length in proportion to the height. Manufactures seem reluctant to increase the wheelbase in direct proportion to the height and really long top tubes are said to make the frame excessivly flexible if standard deminsion tubes are used. So, if the TT deminsion is not too long for you (probably still too short!), it is quite likely that you could fit OK on a bike with an XLT seattube if tight TT standover clearance is not an issue. The one possible position benefit of riding a frame with really tall seattube (and headtube) is that the drop between the level of the saddle to the handlebars can be minimized without resorting to a goofy looking riser stem. This can be a benefit if you want a more relaxed, upright riding position (french fit) instead of a full racer crouch.