Hi,
Well I have a demo and my levelling / PvP experiences are reasonably fresh. The level your at, I found, was a bit in-betweeny as you are not quite in reach of your lvl 60 goodies and enemy CC's and dps is quite hard to counter.
I can understand your build and going for purge but my experience is most of the time purge will not save you. Therefore it's my newb opinion that the 16 points you've invested to get it are better invest either buffing your fire feats or changing your feat set up entirely.Oh and btw the points invested in armour from the general tree are going to do diddly in PvP so no real PvP beneift in those either.
The weakness I can see is.
To counter enemy and get distance using your feat abilities you currently have 1 ability "Detonate". Nice ability, however this takes time to build up and use as it requires minimum of 1 stack of incinerate on the target. And just when you really need it, you have either been CC'd already (smart players will KB, Stun, fear and/or silence a demo) or it just won't work. The other CC you can feat for in the Fire tree is improving your Agonizing Fiery Torment spell by reducing it's caste time to Instant. This IMO would be MUCH better than purge, and is far more effective in saving you than all the other CC's you have, as it gives you a nice instant stun ability,plus 1 root and 1 KB. All this along with a nice instant Hell Fire Stream to add to your instant Shock all increases your chance to escape to live a few seconds more to do more damage and add another CC before nuking the life out of your attacker.
So when you get jumped, insta stun > nuke 1 stack of incinerate > root > add more stacks if needed > detonate > nuke to finish off. Don't forget to break out the beers and barbecue sauce to enjoy with your freshly fried ganker.
Sounds easy doesn't it ? I wish !!
Don't forget your Planar Shift spell that can save you from a few nasty melee hits invaluable when you see a melee DPS looking at you with XP signs in their eyes.
The other option is to focus on the Havoc Tree and go for the instant cast Wicked bolts spell. It's quite high up in the tree so it takes a few points to get there. This would give you 1 instant KB (very handy for charging sins and Barbs trying to stun / KB and HoX's in human form as you can interrupt them if your quick enough. Against medium and heavy armour you need more points in it. The advantage of the Havoc tree is bigger nuke damage, nice pet buffs, self buffs and greater range (this last one is great against Rangers at max range who think you can't reach them ). After 60 there are some great feats for buffing your health and resistences to fear and stun. If you go Havoc, go into the tree as far as you can to get 1 feat in WB (minimum) then I would put remianing points into the Fire tree as you will still want to use a buffed FoG spell (faster casting than Shock strike) with incinerate and blistering wounds, as well as your Agonizing Fiery Torment and your Hellfire Stream spells although chance to use these last two will be less as they have a caste time to them.
Very simply, you have to be fast enough to anticipate and counter whatever the enemy is going to do, keep distance and nuke them down.
Here is a level 80 hybrid spec by Sclulm which gives you an idea what I'm talking about and feats I would go for
http://aoc.yg.com/feat-planner?class=44
Try it out,
Enjoy your fry up