Alliance attack bonus

[stairgod]

If  melee and ranged attack max out at level 20, does an alliance attack bonus of 4 do anything? My first officer and I are currently arguing the point of of researching attack and defense past level 4.  Assuming my personal research levels are at 16 for armor, melee, etc, would level 5 defense at the alliance level push my dynamic armor level to 21?  And I assume that siege engines get no bonuses from alliance attack, since they get nothing from ranged bonuses, correct?

[fragmaster]

team research 5 is useless,coz 16+4 provides maximum bonus.