by useing the no prof to save DC you should be okay to good at all of them, but you only get better at the 2 you are prof in.
Im unsure how many classes give a third save, but the feat is very much spending a resource to be better at something, that seems to be working as intended.
that again is a class feature MEANT to make you better (or those near you better) and yes in theory you could be adding two +5 stats and +6 prof that will be rare at best... most likely you will be adding prof + 2 +3s The only classes that get good main stay saves (dex, con, wis) with those stats also prime stats are cleric and rogue... so maybe those will be a bit broken (and TBH I think only rogue mixing this with evasion do I think would cause a problem) a 7th or 8th level paliden with a 16 or 17 cha adds +3 to all saves (amazing) and also to allies within 10ft (okaish if you all bunch up) if you have a fighter with a similar (16 or 17) con and they are prof they have +3+3+3 to the save... +9 if the NPC wizard or druid throws a con save the DC will be 10+stat... since the stat is prime stat (and con isn't for the fighter) lets give them the same 16 or 17 stat... DC 13 the fighter (on there best save) needs a 4 to make it. now if they target his 8 stat or 10 stat they need a 13 or 14 to make it without the paliden aura or 10 or 11 with.
magic items make you better sounds like it is working,
the entire argument seems funny in a thread where so many complain about 4e being a treadmill... when you get better at something isn't that working as intended?