OpiateGuy/Chinky, my situation isn't perfectly analogous to your situation, but for what it's worth...
I snorted H a couple of times before I shot it. After shooting it, I was a IV user for years. Once I got off of H and spent some time clean (and moved to a town with zero H), I eventually started using pharm opiates... orally, then IV. But I found that I couldn't behave responsibly IV'ing them (as in, couldn't support the habit/tolerance) so I went back to using them orally (longer half life, no needle fixation). That is my primary roa and has been for over a year now.
There are a couple of exceptions... on the rare occasion I get ahold of dilaudid or opana ir, I will shoot those, because I feel its a waste to do otherwise. But for my normal oxycodone consumption, I am back to using them orally almost every single day. Very rarely (possibly a dozen times this year), for whatever reason, I've decided to spike a few roxies, but I'm always underwhelmed with the results...
So, it is certainly possible to go the IV route for a while then go back to other methods of administration... but I'll be the first to admit that if I had access to dope, I'd be slamming it, no questions asked.