I've played KDF to T5 in the beta going down the Bcruiser/Carrier route and since early start hit i've played KDF to T3 as Sci/BoP and T3 as Fed as Sci/Sci.
I'm not sure how it is for people on the fed side who play in cruisers and Escorts but as Science i find PvP to be a piece of cake compared to my experiences on KDF side. I can tank as well if not better than the Battlecruiser, see cloaked enemies a mile off, absolutely destroy any player/ship class combo in 1 v 1 and very often even 1 v 2, damage is through the roof with a single EPS console due to beam angles, c'mon being first or second in damage almost all the time on a ship where i spend a lot of my time healing/buffing/debuffing/CC'ing?
T1 & 2 i wasn't doing as well in the sci vessel but T3 came along and honestly the ship is way overpowered for what it is and has many many more advantages over any ship the KDF get up until Carrier, with the recent changes to cooldowns on the carrier that might even be true there too now.
From T3 Feds have KDF at such a disadvantage it's not even funny, the fact that KDF players think/say things are balanced from then on is simply testament to them being better players in general and most Feds being out of their league.
Edit - I know gear is a dead horse subject, but the amount of blues you get on the Fed side is unreal you get blue almost everything mostly via quest and some through drops. Some of it has insane extra stats like blue heavy cannons with +15 turn rate as bonus stats lol.
I agree T1 space favors klingons as they start out in MK 2 gear all around, even some greens. I found very little space items to buy with pvp or exploration merits as there was nothing to really improve upon. Maybe if they started klings in all MK 1 greens so they have something to improve upon and something to spend those points on.
Most feds usally start pvp with some MK 2 gear, but most usally end up with alot of stuff they still could improve upon.
As for Tier 2 favoring feds in space, that might be somewhat true now till the klings get their tier 2 cruisers.
BoPs are more manuverable, which means once a player is used to that they can stick to a miranders blind spot fairly easily.
The gear is justified (though maybe slightly over compensated) as remember Feds will have been picking up loot/drops and getting quest rewards and buying stuff on the exchange etc... upto level 6, Klingons start at 6 (after the orientation quest) and so need a chance to have a level setting, The idea of just depositing 600 medals into there character instead of the gear is pretty cool though.