lol, i find it funny how the math got done so badly on this. 175 xp in 5 min? come on, make some real numbers to support your argument, even the most crappy of pt make more xp then that.
fighting IT+ mobs usually nets 200 xp every 1 and a half min. one chain to c5 gets you 1200 xp, and takes around 10 min, plus a downtime of 60 to 90 seconds after chain. this method makes 4.5k to 6k an hour.
im not gonna try and say that chaining VT doesnt make good xp, but to make more then 6k an hour you need to make chain 7 or higher consistantly. lv75 commonly xp on VT weapons, and the pt that make over 7k an hour usually make chain 8 or higher consistantly. my point being that chaining VT at mid levels will at best make the same xp per hour as chaining IT+. being that it can make the same xp, some people may like xp on VT better, but its certainly not some superior way to xp at lower levels. (and of corse there are exceptions, iv had several pt chaining IT+ that made 7k an hour, but that has to do with how well your pt is set up and how well equiped everyone is)
also, chaining VT causes a problem with lack of mobs in most areas. you can go to delkfutts at 60+ and chain VT there, and every mob dies in under 45 seconds, but then you kill all 10 jotunn on the 11th and 12th floors in 7 minutes, and realize they take over 10 min to respawn. your left sitting and waiting on repops for 3 or 4 min, or fighting EM bats for next to no xp. god help you if theres another pt there, then you might get 7 of the 10 pops, which will all be dead in about 5 min, leaving you waiting another 5 min for repops.
in my expirance, how good xp is depends more on how many other pt there are in the area pulling mobs from the same place you are. if bibiki bay is packed full of pt, but moon only has 1 pt your lvl, then moon is gonna make more xp even though the mobs take longer to kill, simpley because you never have to stand around waiting for a mob to pop.