I gave a glowing account of my experience with ETS. Here are some points related directly to your situation:
1. Obviously the sympathetic nervous system is there for a reason - not just to allow us to blush. But an overactive system can cause elevated heart rate, and BP. My heart rate was bang on 100 prior to surgery. Luckily the ABSENCE of the other 'uses' of SNS i.e. after it has been severed, WORK IN FAVOUR OF THOSE WITH ELEVATED HEART RATE AND BP PRIOR TO SURGERY. My pulse is now around 70, and my blood pressure a little lower than before. (I have become fitter as well, so not all drop in heart rate is attributable to surgery.)
2. As I exercise I remain pale. I cannot make my face red, other than by standing on my head basically. And certain medications bring on a bit of colour. When I work out I get a bit of sweating on my back. But if I fixate on it - rather in the manner that someone tries not to blush - it comes on stronger. This happens one day in 50 or so.
3. The results have very much lasted for three or so years now; there seems no way that a severed or ablated nerve can spontaneously re-connect. In fact the problem is more that the procedure cannot be reversed! (For those unhappy with it)
4. As I mentioned in my story, I had phantom blushing - the full on experience of a blush; but face pale - for some years (!) before I realised that my face was pale. That is a bit rare. Now - for the last year or so - that I know it's a phantom, these sensations of blushing have faded. Because I'm secure in the knowledge that my face is pale, the phantom blushing is diminishing pretty rapidly
5. I'd avoid the clamping method, which allows a theoretical possibility of being undone. But I don't think it has really ever been successfully undone, and just creates complications. Why not just 'fry' the bastards, and be rid of your problems.