You know I had to pull my uniform out of the closet this morning to see how I have my rack set up and you're right. The SSDR rates lower than the Army Reserve Components Training Ribbon.
I think that is Bass Ackwords though. The SSDR should rate higher as it is not an Overseas Service Ribbon of any sort and definitely not a training ribbon.
Kind of like the unit awards, the NUC and MUC rate lower that the Army's unit awards even though they really should be on par with the army version of the same award. I guess the Army deems it necessary for some reason.
And you are right, our racks are similar. I was Active Marines, then went Reserve Marines, then Reserve Army and now WA National Guard.