The OE spacers won't change the ride. Compared to a BP-51; that is harder to answer because you have adjustable rebound/compression settings based on your load and desired feel. If you dial them in based on the roads you drive on most, the BP's will be better. Generally speaking, highway to highway comparison I would say the OE suspension is better from my personal experience with both. However, once you drive off-road or and/on corrugated roads or even roads with pot-holes, you will grow fond of the BP-51 suspension.
If you aren't ready to take the leap into the suspension yet, you could swap the rear OE springs to the OME 2721's which will add about 1" lift. The OME chart will tell you 0" but that's not correct. The 2721 springs will get you about +250lbs over OE. Feel free to call any time.