The main problem is that controlled release come into higher dose... It's always better to start at the lowest effective dose! If someone start the propranolol long acting form at a dose of 60 mg or 80 mg, it will affect the blood pressure and give more side effects... I think that for SAD and GAD, it's better to start low since too many side effects from high dose can increase anxiety.
Also it depend where you live...here in the canada, the metoprolol controlled release in the lowest dose is 100 mg... That's too much...
Also, the older beta blockers like the propranolol lead to an upregulation of the beta adrenergic receptors in long term... So that's mean that you need higher dose to have the same effect. Only the newer ones like bystolic or the Coreg don't cause upregulation of the beta adrenergic receptors...
The propranolol is the gold standard RX beta blocker for anxiety, but that's not mean that the others don't work...
And don't believe that the fact that the propranolol is entering in the brain in high concentration will help more with the anxiety... The effect on the brain is not related to a reduction of anxiety but more central side effects like insomnia, vivid dreams, visual disturbances, depression, lethargy and extreme fatigue, just to name a few... Same apply for the metoprolol who also cross the brain barrier...
I did tried the atenolol, nadolol, they are hydrophilic so don't enter in the brain but both lead to extreme fatigue and didn't had less side effects...
Keep in mind that beta blockers are heart meds and not approve to treat anxiety...an antidepressant can do a better job to keep anxiety at bay, if you can tolerate them...sadly I can't...also benzo meds are good for gad and sad... But addiction occur most of the time and you get stuck on high dose of clonazepam like me, 8 mg day, with no effect on anxiety... After many years of daily use...