I've posted my experience with Scott's Ohlins shocks on several threads, but since this one has the key words in the title, I'll repost my comments here to make them easier to find.
One of my rear shocks was getting worn by 60,000 miles, so looked at the options. I considered the Penskes too, but the general word from those with them was that they are harsher than the stock shocks. From what I could gather, the Penske's are designed for racing, so NVH is not high on the priority list. From what I could also gather, the Ahlman shocks had enough adjustability to soften them up for street comfort. Since the vast majority of my many miles are on the street, I chose the Ahlman shocks. The followup decision consisted of whether to opt for the 2-way or 4-way adjustments. Considering that the 4-way adjustments added about $2000 to the price, after discussing it with Scott, I opted for the 2-way adjustments.
The Ahlman shocks work much better than stock and a huge advantage is the compression and rebound adjustability. The adjustment knobs are easy to reach and change by hand. Scott delivered them with the adjustments set for my mix of mostly street and occasional track driving, which was roughly in the middle of the adjustment range. For street driving, I have loosened up the front and rear adjustment knobs to 2 clicks from the minimum. That softens the ride noticeably and the ride is significantly more compliant and comfortable on the street than the stock shocks, particularly rough roads. When I go on the track, I crank them back up to Scott’s recommendations. Best of both worlds. They also work correctly with lowered suspensions.
After driving them several times on the track, and 10,000+ miles over the past 2+ years, I highly recommend them. I think that if you will be driving your car on the street, or mixed street/track use, this is the hands-down best option. For a track-only car, you would need a stopwatch to determine what's best for your car setup.
2-way versus 4-way adjustments: The 2-way adjusters allow changing the low velocity compression and rebound damping. The 4-ways allow additional adjustment of the high velocity compression and rebound damping. Thus the 4-ways allow different damping curves for low velocity and high velocity damping. I don't know how useful this is on the track were the pavement is pretty smooth--Scott would have to offer his experience on this question. But, after driving them for 2 years, I think the 4-way adjustments would provide more advantages for the street, where pavement cracks, potholes, patches, and the like cause short sharp suspension movements (high velocity). The 4-ways should provide a smoother ride on crappy streets. If $2000-ish isn't a biggie to you, I suggest you spring for the 4-way adjustments. I've thought about sending my shocks back to Scott to get the additional adjustments added. if I were ordering from scratch today, I would opt for the 4-way adjusters.