She's got subpar durability in the DL, sure, but even "bad" durability is still a-OK in the Dungeon where things like buffs & team healing exist. From the stat topic, endgame Jane has .85 PCHP, and .94 PCHP without Zed (Floors 1-6), and 63% evade. Even if someone on the Dungeon team can ITE OHKO her, that person won't always go first, thus wasting the turns of the faster people who still didn't OHKO. This is pretty awesome. (Just the old Loreleai / Killey fight was a fight where she can only mitigate the damage by eating half of Lorelai's blast rather than cheese turn 1.)
As for her durability... assuming that WAACF defense is subtractive (stat topic claims it usually is), Jane takes 51 damage more than average. Off an HP average of 1467, that's either + 0.03 PCHP damage flat, or 109% normal damage if scaled percentage wise (~.43/.40). That's annoying but not "tissue paper." (Of course the non-subtraction formulas in ACF might punish Jane's bad defense more heavily, I have no idea.)
I might be willing to take the evade a little less seriously though since if ACF is like WA1o, 90% of everything in the game is ITE anyway, so evade hype is kind of meh.
Ninja edit: Snow is different because Snow's taunts only go off at average speed, enabling the faster Dungeon enemies to run riot. Firefly is awesome because it's on instantly, and Jane's is awesome because she's fast and gets to use Sucker while it's still relevant. Jane's hit rate is probably higher, too (since it's 90-100%, while the odds of Snow getting everyone vary and lag a bit on early floors when he only has 4 shots). For sure, Snow's flexibility & durability are advantages Jane doesn't share, but eh, Jane's also got Follow Me hype later.