I have the Jem Hadar Attack Ship since the first day it was in some lockbox (first or second key). It was last winter if i remember correctly. Since then, no other ship could be compared against it with the class i usually play. Now i have the Fleet Defiant and am happy that i can finally jump on a federation vessel again. Its not exactly as good as the Jem Hadar ship but the gap is not so big that i would have a problem with.
My only complaint remains that I find Federation cloaks pretty useless, since I can use the subspace jump console to put my ship in position, which I realise means I lose the +15% decloak bonus, but am still nonetheless in a good position to initiate an alpha-strike.
Not sure what you mean. You can use the cloak with the subspace jumper and it auto-decloaks you as soon as you subspace jump behind your target.
You should still have the +15% bonus on top of appearing right behind your target.