Before struts, most cars had shocks. I always found that the OEM shocks only lasted about 20K - 30K miles. Once I would change them, there was always a remarkable improvement in the way the vehicle drove and handled.
I know that the KYB Excel-G new struts I put on all four sides of our '05 OB are much different than the original struts, even when the car was new. The factory struts had a "baby-carriage" feeling to it, not tight and not good on bumps and washboards around turns. These new struts are like driving a totally different car, that is how much difference they made. I tried the "bounce-test" on the front and rear with the old struts before I removed them. Jumping as hard as I could to get the car bouncing, I did all I could to even move the car, let alone get a full bounce out of it. So, the OEM struts were still good, just not nearly as good as the new struts!
If you are changing the springs, I would wait until you can do the struts all at once.
I would say, at the mileage you have, you WILL notice a big difference!
If the old ones are not leaking, you may find someone willing to buy them if they damaged their struts in some way and just want a replacement, or if they are installing Konis and need just the old shells to insert the new Konis into!