Droid X2 is likely to be a Tegra 2, but that isn't known for sure yet. It will definitely not be LTE though. The specs of the revised Bionic have yet to be released, but it will definitely be dual-core LTE. It will almost certainly have 1gig of RAM, and will have either a Tegra 2 or TI OMAP4 SoC. Both are powerful dual cores, though the TI is a little newer and better. The LG Revolution is LTE but is NOT dual-core, unless LG decides at the last minute to swap it out for the Optimus 2x. That's unlikely, however, as it apparently takes awhile to design an LTE device at this point in time. The Samsung Galaxy S2 will not be outclassed by anything this year, and may very well be the most powerful device of the year and sometime into next year, until we see Cortex-A15 phones coming out.
The Galaxy S2 has not yet been officially announced for VZW, though rest-assured it is coming. Hard to see when it will fit into their market strategy, however, considering they're just now launching the Charge. They wouldn't want to release another LTE Samsung right away and kill Charge sales, yet it wouldn't make sense to release a device this powerful and not have LTE capability built in. While I would love to see an LTE GS2 in June, that is highly unlikely. The most realistic scenarios are either an early fall launch for an LTE GS2, or a late summer launch for a 3g version, followed by an LTE version this December or the beginning of 2012.
Still, if you're considering VZW and have LTE in your area, you'll love the speed. I don't know how I feel about some of their changing policies, but if you lock yourself into an unlimited LTE plan now you should have nothing to worry about. I'm sure you'd be happy with a Charge now, though you could wait a bit to see how things play out regarding the Bionic, the end of unlimited data, and anything official about a GS2.