Anyone ever tried 2x100Watt Bi-Amp Vs 200 Watt

If the cost of additional cables doesn't matter, which way is preferable?
Bi-amping 2x100 watt can effectively be more powerful than 1x200 watts. LF and mid/HF driver simultaneously have such vastly different needs while playing. This does not gurantee a better sound, that depends on your speakers and the amp. But in general it is a more efficient method of powering your drivers so theoretically preferred.
The main reason is not so much a power issue but that of driver modulation. A woofer that moves like a jackhammer to make any bass will generate a fair amount of back EMF, the result of inertia causing it to behave differently than the input signal; biwiring does remove some of the back EMF from feeding back and modulating the mid and tweeter but not as much as a biamp configuration.
I run the front r/l speakers in my home theater vertically biamped using 2 Electron Kinetics Eagle 4 amps (they're 2 ch @125 w/c). This configuration is far better than any other I've tried (and all other amps too. (see my system page "media room for one"). The speaker designer (Albert Von Schweikert) recommended this over using one higher power amp.

The only extra cabling it cost me is a "Y" adapter on the I/C. Even when I didn't run biamp, I still had bi-wire shotgun runs because my speakers require it.
given that you are considering a decent amp, and not one from walmart--

My advice is that if your speakers have only one set of terminals on the back to go with the 200w amp instead of the 2x100w. you have a greater chance of degrading the signal or introducing a problem than to recieve benefit. if your speakers have two sets of terminals (that are bridged, you remove the bridge when you bi-wire/biamp) then two amps would increase your chances for a non-negative result. giving you greater control over how much amp goes to the highs and what goes to the lows... Don't forget that many amps are bridgable, so you could wire two 100w amp channels to the same speaker to get 200w that way too.
Wow. Lots of opinions. IMHO, a good 200w is superior in terms of power availability. The reason is that most of the power is utilized in the bass and with 2x100, the woofer/LF will still see only 100w. One can argue that bass stress will not affect the HF with 2x100 but by doubling the power to the LF, such stress is minimized.

Also, bridging is different from 2x100 and requires a phase inversion device. The result is usually more than 200w but places limitations on the impedance sensitivity.
Biamping was very effective back in the days when power amps had high IM distortion, and watts were expensive. The only valid reason to biamp today is to get rid of the passive crossover.
I believe I misunderstood your question. For some reason I thought you were asking about vertical bi-amping - 100w for mid/HF drivers and 100w for LF drivers, not horizontal bi-amping - one amp per speaker. So please disregard my initial post.
agree with Kr4. Depending on what you want to achieve, if you are trying to increase SPL then you need to feed it more power. If you are after better sound, vertical bi-amp might give you that.
Done both bridging (Plinius SA100's) and passive biamping. In the latter, I used Monarchy SE100's above 90 Hz and an old Mission 777 (100W) for bass, along with a custom attenuator to accommodate gain differences. This setup took advantage of both amps strengths and fit my budget at the time. I'm not sure a dozen Monarchy's stacked in parallel could have matched the Mission's bass, despite the identical rating. A higher xover would make matching more difficult with amps that aren't identical.

A friend matched a Coda System 100 for bass with Manley Snappers (100W tube) and there was only a slight gain difference.

The other thing that should be considered is that input impedance drops with passive biamping. With a few exceptions, that should not be a problem.
Speaker impedance neither drops nor rises with biamping as a rule. There are few exceptions. If Ngjockey is referring to the input impedance seen by the preamp, that does drop but most amps have such a high input impedance that even halving it still presents a reasonable load for a decent preamp.