I actually built a street-slum physad for a low power game (many many moons ago), and most of the above qualities were indeed utilised. Updating the concept to 4e, the following would probably apply:
In his local gang, he was the scout, so he had the athletics/stealth to climb into position, stay hidden, and accurately
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Improved Athletics and
Stealth for the positioning requirements
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Enhanced perception,
Low-light, Thermo and
Eidectic Memory for the perception and reporting requirements
Living on the streets, he had to have other useful powers to survive
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Iron Guts and
Sustenance to survive indefinitely on low-volume, poor quality food
My guy was definitely a '
Flight' option (in terms of a Fight or Flight mentality):
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Combat Sense for when he was getting ambushed
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Freefall for those daring escapes
With a long-term campaign and post-initiation karma, he evolved to be a good close combatant and infiltrator
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Killing hands, Critical Strike, Elemental Strike, Penetrating Strike- Martial arts according to flavour
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Smashing Blow (bye bye barriers)...could also be replaced with
Elemental Strike (Blast)
As I was GM'ing another campaign with the same players, I deliberately chose a low Charisma PC in this one to stop hogging the spotlight

However in 4e, a few BP into Charisma and Linguistics options could make the PC a secondary Face-archtype pretty easily