Virginia gets mediums, yes. Mediums allow for an impressive set of spells (including Floor 1 revive, despite being just ST) However:
Jane doesn't get any respect before Floor 3/4 for a reason. Follow Me apparently comes in around then. This allows her to give turns to other people (Sort of a selectable Turn Shift). Aside from that, she...doesn't have much at all in anything, Dungeon-wise, aside from speed.
Billy has solid power (and can deal magical damage indefinitely thanks to his Ether guns), alongside awesome MT healing (that he starts with) and Xenogears haste (that he also starts with). He also gets revival later on. However, he is slow before the haste. And frail.
Jude...well, he's fast, and his abilities aren't too bad. However, they're relatively expensive for what they do, and he doesn't benefit so much in a non-HEX format. To boot, his signature abilities (Assault Buster, Silver Launcher) come in around Floors 6-7, as do the Howling Spike abilities. He also ends up totally blowing against magic.
[EDIT] The stat boosts from Ley Boost last for very little time. The only one that people consider is his MP recovery, which is just plain SLOW, though viable during totally locked-down fights. Leypoints are often not considered aside from, arguably, Arnaud's Jump FA.
And just like in-game, he doesn't get the two skills of Kresnik's that actually mean something. God knows he'd be even nastier if he had Adrenaline Rush and Healing Factor.
There's no real synergy to this team (Aside from Follow Me possibly compensating for Billy's poor speed). It's a joke team of sorts, but that's about it.
I'm likely to, once school starts to die down (amazingly, cranked out a quality paper at 4 AM), actually try to formulate a team using the guide. It'll probably still crash around Floor 2 or Floor 3.