Sometimes pogo sticks are fun!
Using the shock in the lowered position puts the linkage in a different part of the leverage curve I guess but it really should not change the basic leverage. As the rear of the bike goes down, the weight transfers to the rear as well. When the rear shock is used in the "low" position, the spring clip should be flipped and that puts extra preload on the spring as well as positioning the big steel washer to restrict the shock travel so the bottoming point on the suspension is still the same (this avoids the wheel hitting the fender or the skid plate contacting the ground sooner than intended. This reversible spring clip is one of the reasons there is so many threads above the spring on the shock body.
If we build a short version of the shock, we can not keep the convertible feature. The shock is purpose built to give the low height and proper spring preload. Since spring rates are relative to the travel, reducing travel will make the required wheel rate be higher. In other words, the less travel needs a stiffer spring, all things being equal.
With regard to the DRZ shock, the new DR 650 shock is giving better performance that the Dz in Dual Sport use. I owned a DRZ E that was street legal up until last year and my friend Jerry (a DRZ s owner) has ridden on my DR with the new shock and wants me to make his DRZ work like the DR does. The adjuster on the DRZ is better than the stock DR but I really have no idea how it will work on the DR. Is the eye to eye length and stroke the same between the DR and the DRZ??