The idea of markup is to capture information explicitly.  To capture explicitly the information that two pAdas make a line and that two (or sometimes one or three or more) make a verse, one needs different elements for pAdas and for lines.  That is why I use the seg element, which conveniently does have a type attribute to specify what it is.  caesura or space elements also are useful for marking the location of breaks, but don't explicitly mark pAdas.  The lg/l/seg markup is as easy to process as the other alternatives proposed.  We send lg elements with l and seg children to our meter analyzer without a hitch using regular expressions to extract the text.  Rendering is also not a problem.  Putting four lines in l elements leaves the problem that Anustubh meters usually put two pAdas per line with sandhi while longer meters may not.  An l-element was conceived for a line, not for a pAda.