Guild Thief before Ninja Spy?

[Kershek]

Party makeup: 5th level melee-heavy human cleric, a human evoker, an elf rog1/rgr4 two-weapon/archer combo, and my character.

My last rogue was eaten by an assassin plant recently and I'm considering my options as a new 5th level replacement.

I'm looking for a melee fighter that likes to flank. The last rogue had a +1 wounding rapier and the party managed to rescue it, so I want the new rogue to take advantage of it. I have both a swashbuckler/duelist build and a rogue/ninja thief build in mind, but this post is focused on the latter choice.

My question - is it worth going into Guild Thief from the FRCS before heading into Ninja Spy (Oriental Adventures)?

It would either be Rogue 7 / Ninja Spy 10 or Rogue 5 / Guild thief 5 / Ninja Spy 10.

I'm interested in the character fighting flourentine if possible. He is also a socialite with a focus on psychological manipulation. I'm sure I can find good two-weapon feats (or other feats) for the two free guild thief feats, but I'm wondering if putting off the Ninja Spy is worth it. Upcoming feats are Combat Expertise, Improved Feint, and Improved Two-Weapon Fighting.

Here is the build I have. It's a 40 point character and the wounding rapier is not in the stats until he actually meets the party.

Human Rog5: CR 5; ECL 5; Size M; HD 5d6+5; hp 27; Init +4; Spd 30 ft; AC 19, touch 15, FF 15; BAB +3; Single Atk: +7 melee (1d6/crit 18-20, Rapier) or Full Atk: +5 melee (1d6/crit 18-20, Rapier), +5 melee (1d6/crit 19-20, Sword, short), +8 ranged (1d4/crit 19-20, Crossbow, hand MW); SV Fort +3, Ref +9, Will +3; AL CN; Str 10, Dex 19, Con 12, Int 16, Wis 12, Cha 16.
Languages spoken: Common, Dwarven, Elven, Draconic
Skills: Appraise +5, Balance +9, Bluff +11, Climb +5, Diplomacy +7, Disable Device +11, Disguise +18, Escape Artist +12, Gather Information +7, Hide +9, Sleight of Hand +7, Jump +7, Listen +3, Move Silently +10, Open Lock +12, Search +11, Spot +9, Tumble +14
Feats: Dodge, Two-Weapon Fighting, Weapon Finesse.
Possessions: Gloves of dexterity +2, 2 Potion of cure light wounds, Cloak of resistance +1, Ring of protection +1, Hat of disguise, Rapier, Short sword, Studded leather MW, Hand crossbow MW.

Any help would be appreciated. Thanks!