It's going to be important to know your KH first. Since high KH prevents pH from dropping, you might see little to no effect.
Knowing how they worked for others also isn't helpful unless you know their KH, and probably their tap pH and water change habits.
I put 5lbs of mopani wood in a 56 gallon column tank. I have really soft water so I supplement the water up to 3-4 GH and KH. I liked the tint, in fact let it get pretty dark, and the ph dropped a little. Wanting to keep the tannins but not go acidic I consulted LFS (a large store on the same water supply as me) and was told all I needed was KH of 4 to keep ph stable. They were right it had slipped to 3, and bringing it up a touch now keeps my tannin-filled tank stable. The pH stays at whatever it was out of the tap, so far.
I've heard different explanations of how peat works ... Whether it adds acid or reduces KH. I believe if it just adds acid you'll see no effect if you have high KH. Or you'll see bouncy ph. If it reduces KH and adds acids then maybe, but I also hear a lot about instability this way.
So anyway. Driftwood might do nothing but stain the water, but it probably also wouldn't hurt if you have high KH.
Still I wouldn't try to move your ph without a better understanding of how hardness and ph are related. There's a reason craigslist is full of ads for cheap fish tank setups "only used for a few months, comes with ph up, ph down, proper ph, an almost full bottle of fish food, ich treatment, antibiotics, and melafix."
Sure peat and wood and coral and all that are natural and don't change things as drastically as chemicals but changing pH is like putting brakes on your car: not something that's extremely difficult to understand, but something you don't change until you're sure of how the parts relate.
Sent from my iPhone with three hands tied behind my back.
