Are any of you yogis against getting X-rays and such done?
Certainly, I can only speak from my own experiences with X-rays and CT scans. As a yoga teacher, holistic health advocate, do I support the use of X-ray and CT scan technology? Yes and no, depending on the issue. If it was something causing me pain, after failing to fix the issue myself, I would use a scan to help give me a better picture of what was going on. Of course, these scans also help practitioners who work with you like chiropractors, doctors, physical therapists and other bodywork specialists, who cannot feel your pain, to understand your issue better. At least, these can help from a simple musculoskeletal alignment point of view.
Sometimes, and especially if you are new to physical yoga’s development of PROPRIOCEPTION, these scans can help you visualize your issue which can help your yoga practice, to pin point key areas. That said, it’s not going to fix your sciatic issue, just as all the X-rays and CT scans I had on my spine did not fix my hyper-kyphosis, it’s just a picture. But I was able to see a little better, at least at that early point in my yoga practice, where some of the misalignment might be causing me pain. It is important to NOTE, that just because it is your sciatic that is bothering you, does not mean the problem lies only in that area. When one part of the body is out of alignment it throws off the entire kinetic chain. This commonly causes pain outside the actual source of misalignment. I hope that makes sense.
Radiation is not something to have a party with. These scans obviously need only to be used when benefits outweighs risks, and of course used very sparingly. I will tell you, I have had over 10 X-rays and 1 CT done on my spine while I was going through some vicious surgeries. It has been several years since and I have not developed any noticeable complications from the X-ray and CT radiation. However, I am also in very good health after dedicating a lot of time in the last several recovery years to YOGA. I believe my yoga practice has protected me with strong immunity from any risks western medicine imposes.
The surgeries my doctor recommended for my chronic back pain, as aggressive as they were, did NOT fix my issue like as intended. The only reason, I bring this up is because for you or any one reading this, if surgery is recommended and you feel like you have tried everything, you probably haven’t. There is always something else to try, btw there is over 8000 yoga poses just as a polite suggestion. There are also, many forms of mindbody work out there, naturopaths, excellent chiropractors (not all of them are the same), acupuncture, aqua therapies, blah I could go on for a LONG time and there so much I don’t know of yet! Perhaps even the same stuff you have been doing but performed in a different regiment? Surgery is the LAST LAST LAST LAST resort! It is an emergency! Surgeries are usually permanent but always inflict trauma upon the body that is hard to correct. In my case, surgery made my issues more complicated.
certain yoga poses actually made my injuries worse though
There could be many reasons for this, many more than I know to suggest you research.
I know fo cases where pain conditions can worsen after a few weeks of using a new exercise(s) in yoga. Assuming you are using a qualified yoga instructor to guide you, this increased pain should not be a discouragement. Pain from new exercises can become worse even after 2 months of daily practice. However, given continued dedication to the yoga practices it is possible to eliminate the pain completely. It can take time, like 8 months while the body transforms on the inside.
And of course, it is important that the postures are done correctly from beginning to end. It is important to go in a sensible progression from one posture to the next so that you are warmed up for more complex movements. It is important that you know you are in alignment, or at least are guided by a quality teacher to be sure you are in alignment in the poses, because YES, with many of the yoga postures, when they are not performed correctly you can hurt yourself badly. I have done this! 
If you are out of alignment in the pose you are strengthening the MISALIGNMENT. You can easily pull tendons and muscles this way causing more misalignment and requiring longer recovery time as you will be sore for, perhaps, days and will not be able to keep up a consistent practice.
My own sciatic issues have be helped very much with a yogic massage technique taught to me by my long time guru who has been teaching for over 50 years.
Sciatic Self-Massage
-Sit on the floor
Legs stretch long
-Hands out behind with finger tip facing body
-cross left leg over right
-pull in your abdominal
-inhale, lift legs about 8-10 inches off the floor
-you can lean back using your hands to prop you up
-rest on the left buttock, breath freely and fully in and out
-message the sciatic by pressing the left buttock into the floor in circular motions, one way and then the other
Switch sides! 
If you are out of alignment in the pose you are strengthening the MISALIGNMENT. You can easily pull tendons and muscles this way causing more misalignment and requiring longer recovery time as you will be sore for, perhaps, days and will not be able to keep up a consistent practice.