Dear Angermines,
Theobromine, or more commonly referred to as chocolate caffeine, along with the caffeine found in coffee, is classified as a methylxanthine. It is several times weaker than coffee caffeine though, so the "buzz" you'd get would be much less. And even so, a weak "buzz" is better than no buzz at all, and I can't see how taking any such stimulant will inhibit gains in any direct way.
Still, many people enjoy the pleasantries of indulging in chocolate - it is a comfort food, especially when laced with ample sugar as you would find in any standard Hershey's. There is probably a host of beneficial fats found in cocoa butter - probably anti-oxidant in nature and whatnot but this is no reason to start chomping the stuff down by the bucket.
And the problem with chocolate is just that - the high caloric content. This tends to make it a diet no-no. I am unsure of the endomorph-chocolate relation but this must stem from the fact that endomorphs are often prescribed a stricter diet than their ecto or meso counterparts and by this token, the caloric dense chocolate becomes off limits for the endomorph.
If you wish to enjoy the healthful effects of chocolate but without the added sugar, see if you can get dark cooking chocolate. Or if possible, Lindt has recently released an 85% cocoa chocolate bar - this is strong stuff and definitely not for the faint-hearted or sweet-tooth. A small cube of it actually curtails my appetite, believe it or not.
On a final note, count your calories and macronutrients. If your taking of 60-70gm of chocolate a day is well within the confines of your calorie/macronutrient needs, then to hell with whatever else might be of concern
Godspeed, and happy HSTing
