So one advantage of paragon mutliclassing is that you can 'trade up' what would have been your paragon powers for higher level powers in your second class. You can't do that with paragon path powers.
That said, it's really only an increase in flexibility. In order to trade up powers from your second class, you have to forgo trading up powers in your primary class.
Not sure what you're getting at, but you've definitely misunderstood lkj's point. He's saying that, according to Customer Service (take that for what it's worth), when you take the paragon multiclassing option, you can upgrade the powers you pick up at 11th, 12th, and 20th level once you get into the epic tier.And?!?
This is what makes the option worthless. You end up stuck with lower level powers than you would have if you'd just taken a PP.
Some, not all. Mask is making the assumption that he will have enough wealth to convert to into all the stuff he wants and extra weapons of the right type. I doubt that.
1) This is a limp way to design. 2) Any non-multiclass character can already swap out its own powers at every level. By your logic, this has the potential to get out-of-hand as more splatbooks get released (e.g. Fighters will get game-breaking combos once the Martial handbook comes out in October).Missing any class or paragon features now does seem to make it sub par. However I think this is to proof it against any future too good combinations - as you can cherry pick powers this option will become stronger the more powers & classes there are to pick from.
But it does cost you tons of power from the paragon path you would have chosen.Are the abilities less powerful in raw terms? Yes. That less amount of focused power, however, is the cost for more broad application of power... especially seeing as the multiclass paragon path doesn't cost you any abilities or powers from your -primary- class, which you still receive in abundance.
But it does cost you tons of power from the paragon path you would have chosen.
Yes, the versatility gained from multiclassing should cost something, but giving up 3 bonus paragon path features to replace one of your at-will powers is not an even trade. I'd say that the at-will swap is worth one of the paragon path 11th level path features; there's your price paid for versatility. Replace the other 11th level and the 16th level feature, and you've got a route worth exploring.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.