Welp. I can tell you as somewhat of an expert. An A+ decked out melee Whm versus a same class of thief, the thief does almost 2x the damage, and that's not on EXP mobs, not EP's per se either.
Is it worth it? Yes
Is it fun? Yes
Would it be viable in a merit pt? If it was a Brd, Cor and 4 Whms sure.
What's the best settup?
Clubs:
1) Perdu/Antares. Speed wiht standard WHM gear, you swing faster than a decked out thief.
2) Morgenstern/Perdu. Awesom combo, Morgenstern is really slow and the 6% crit only affects the first hit on WS.
3) Perdu/Templar. Good combo added bonus of cure potency.
Builds:
Haste:
Turbo turban
Prudence Torque or Peacock Charm
Brutal Earring
Suppanomimi
Goliard Sao or Noble's Tunic, refresh is hard to pass up, even for 4% haste.
Blessed Mitts
Rajas Ring
Sniper Ring of some sort.
Altruistic Cape, or Boxer's mantle. Honestly see no diff in evade rate.
Swift belt
Blessed Trousers
Blessed pumps
WS
Marduk Tiara
Prudence Torque or Peacock Charm
Merman's Earring (Brutal's high risk of deminished returns on a 6 hit)
Merman's Earring
Tabin Jupon +1
Healer's Mitts +1
Aqua Ring
Aqua Ring
Prism Cape
Potent Belt
Blessed Trousers
Marduk Crackows
Merits:
Club 8/8
Divine 8/8
Enfeeb 8/8
Crit 4/4
Spell Interupt 4/4
One thing Whm does get over a lot of the melee is a shit tone of Haste gear, and access to thier own Haste spell. Turban, Belt, Body, Gloves, Pants, and Feet, all NQ get you 23, get any 2 HQ and you're capped. add on Haste, and you get a 40% delay in attack rounds, that's solo. From a base including the DW bonus thats a 66% increase in attacks. suddenly that 10.83/8.57 DPS club combo starts looking a little better. Throw in some really decent 298 skill enfeebles, stoneskin, flash, cures, and you got a decent settup for Whm.
I personally always wanted to try the melee Whm thing out in an actual parsed 'for real' merit pt, but the person that's good at it, and owns the above described character(sans Goliard Sao and some enfeeble gear) knows better than to waste a merit slot like that.
Honestly you gotta just play it smart. If you like that playstyle set up a group to do it. But a Melee Whm to level up is a really hard thing. There's a lot gaps between damaging clubs as you progress those gaps are less frequent, but the clubs you get are either really slow or really low damage, either way, a bad thing. In short I don't reccomend it, it willl make you a little loopy in the end. Enjoy your melee on the side, don't ruin it by making it the theme of the job.