I think that basing your build on the gamble that WotC will make design errors in future supplements which will increase the relative power level of Warlock powers is dangerous to say the least.
Given the Dragon is going to be legal and the number of design errors they've made in just one supplement with the illusion spells(even after publishing), I think it is highly likely that this will happen. Ultimately, they'll give a handbook to the writers of Complete Mage or Champion to edit and they'll do something stupid. Mike Mearls can't do everything. 20 Temp hit points that an Artificer gives out at 2nd level is another good example of this.
And if it doesn't, I'm happy with the utility I get from being able to attack in melee or at ranged. I value that more than I do the paragon paths as I'll always have a good action vs having a great action some of the time - a situation that flying opponents often cause for melee builds. That's one of the biggest design flaws in 4e.
Under RAW, your build will require two implements, a holy symbol and your pact blade. How is this going to happen? You mention in your WotC thread that "it seems likely" that a workaround for the holy symbol implement requirement for all (but one) of the Paladin Charisma-based daily powers will appear in the next few years.
Why would you assume this?How is he primarily a melee character? You have one melee at-will and one melee encounter power (whose side benefit is based on Wisdom, which is a weak point for you).
Straightforward enough - the odds are that they release more Paladin powers that are Charisma/Weapon. As those powers appear, I'll take them over ranged implement powers(as I use Warlock specials for range)
The Martial Power book should solve that issue. I don't want Radiant Delirium - I'll take it because it is the best choice for the level and I'm very effective with it
And even if that doesn't happen, all it means is that I do a ranged encounter power as my opening move, then move up rather than move up and do a melee encounter power. Because that's not my best move, I won't invest in an at-level implement solely to boost one encounter power by a +1. I'll invest the gold in something else.
I didn't notice your low Wisdom when listing the weaknesses of this build. Many of a Paladin's powers (as well as Lay on Hands) have a secondary benefit which is Wisdom-dependent; your low Wisdom is really crippling you here.
Hope it works out!
By the way, your build lists only 3 encounter powers at 11th level. You are entitled to 4.
By around 15th level, I should have no Paladin powers that have strong secondary effect from Wisdom. An extra temp hit point or two is no huge loss as an example. A loss of a bonus to AC or penalty to hit is however. At the moment, there isn't a choice. I'm reasonably certain that they'll release something that does that.
Fearsome Smite is the missing one at 11th, but that'll get replaced presumably.