I got a cortizone shot intra joint about 6 months ago and I knew I would be looking at RS in the future. The cortizone dealt with the pain, that I think was more related to a labral tear than anything else. I'm not 28, I'm 41 and the decreased ROM is really what made me decide to get the RS. I thought with a cortizone shot, I'd just keep going for several years and then get a hip. I just got tired of poor ROM and also the 3 days of hobbling around after any bit of activity. Not to menton getting everything else out of wack.
I'm not sure that you'll want to simply continue with meds for the next 10 years? and then get a hip? That puts you where I am and I too told the doc straight up, that I didn't think I would only deal with RS once in my life (not counting the other hip). I'm just not confident that these will last 40 years. However, even without the long-term studies he was pretty confident that the RS would last 40 years or more. I'm not sure if that is based on those few guys in England in the 70s, or if it was based on this particular surgeon's 20 yr study.
Also, I don't know if deca accelerates deterioration of the joint, but you should talk to your doc about that. There is a possibility that RS would not be viable if there was enough deterioration ethier due to meds or just continued wear. Something to keep in mind.