(for the mathematically inclined, I took the dps multiplied by 2.5 for crit dmg and multiplied by .05 for the addition of the extra 5% crit chance. It's been a while since I took a math class and admittedly the diablo system of figuring damage is a little more convoluted than I care to figure out. If you feel my numbers are off, I would appreciate an explaination into where I did my math wrong)
You're right in principle.
For Archon, for some actual comparisons, I have around 200k DPS with 2 APS so storm Armor would hit for about 100k average for me. My effective dps single target is 600k because I use teleport rune, which makes it 700k with Storm Armor. If I use Pinpoint, it raises my dps by about 7.5% because I have 284% CD and only 31.5% crit (not counting scoundrel). That would raise my dps to 207.5k for an effective dps of 622.5k, which is a fair amount less than pinpoint, so by your analysis you're correct. If you don't need the extra armor from pinpoint barrier, then it seems storm armor can be decently effective.
For CM the comparison isn't as easy. While it seems you can get a higher theoretically dps gain from Storm Armor than Pinpoint barrier, you also have to factor in the extra armor gained, which makes survival higher, and the extra crit also increases survival. However, if you're farming keys, it's probably best to go with the MP level that lets you use the highest dps setup, which means Storm Armor with Shocking Aspect, and lowering the MP if survival is an issue. For uber bosses, I prefer pinpoint because most of the time your dps is just an extra and the most benefit the group gets from a CM wizard is the stunning of mobs, making the fights much easier, Plus, I'm too scared to try dropping the armor buff against Ghom.
Personally, I think i'm going to keep with SA - Scramble for my Archon runs, probably at MP2 since for MP3 I really need the extra armor for damage reflect. While the scramble isn't active a lot, it's still active a fair amount and the speed boost is really nice, especially for annoying areas where mob density can be problematic with Archon uptime, like Fields and the zone where the keywarden is. I can run MP3 with pinpoint fairly well but I like the complete faceroll feeling of the lower MP, plus the easier time with reflect mobs and annoying elites (I'm talking about YOU phasebeasts and demon tremors!). For CM, I'm going to try switching to the SNS spec with shocking aspect and diamond shards, since it's the highest theoretical dps spec for CM. For ubers, I'll probably keep with pinpoint up to MP6-7 and force armor for higher.