Interrupts and Shutdown
I play a mesmer and a ranger and as far as interrupts and shutdown goes they are both good at it, but the differences need to be understood by some of the rangers here. While ranger skills are cheap and spammable, it's not like a mesmer with Cry of Frustration and Diversion is a sissy... those skills can strip a boss bare of abilities. CoF is a HUGE aoe interrupt with chaos damage thrown in for kicks, and it can be Echoed / Arcane Echoed. Wastrel's Worry is ideal to mix in with shutdown, and is incredible against anything with the 'natural resistance' ability (it doubles the mesmer's WW damage output). There's a host of other shutdown options (Blackout, Ignorance, Signet of Humility), but those 3 are my current favourite combo - Cry / Diversion / Wastrel's, leaving room for the rest of my mesmer duties...
Hex and Enchantment removal
There's the whole hex and enchantment removal side to mesmers. Shatter Hex has the aoe of Energy Surge and does 50% more damage on half the recast. It's punishing on a tank in the middle of mobs, similar to Smite Hex but supercharged. Shatter and Drain Enchantment are also reasonable... although personally I prefer necromancers to do this. Inspired Hex and Enchantment are other options... Inspired Hex is great if you can pick up another Domination hex (I had dual Empathy recently

Empathy and Backfire
I like Empathy for PvE, although I don't carry Backfire anymore because I use Cry / Diversion / Wastrel's. There's no synergy there with Backfire. Empathy on the other hand is great, because most enemies attack. Very difficult enemies (bosses) that have been shut down are easy prey to Empathy and Wastrel's Worry, because all they can do is attack and not use skills!
Henchmen
I really laughed when I read the 'can't play a mesmer if you only have hechies' argument, because that's mostly what I do and I very rarely die. I made my first ever attempt at the High Priest quest in Sorrow's Furnace the other day with henchmen and suffered only a single death, completing the quest first try. (Paranoia helped a lot!

If you want your mesmer to soak up hits better, I would suggest an Inspiration stance and a 'while in stance' collectors shield (swap in when necessary), and a single piece of '+15 armour while casting spells' armour (I like virtuoso's gloves). You can wear rogue's armour too if you don't mind losing the energy compared with enchanter's. An energyless heal like Healing Signet is useful but not critical.
My 2c.
The biggest thing would be making the effects more spectacular, especially considering the deceptive radius on Cry and Shatter Hex...