If you love the job you're doing and it gives you a sense of fulfilment, achievement and recognition, then even if you have to work long hours in your job everyday, it'll be a breeze.
But if you detest your job and it makes you feel insignificant and discontented, then working at your job for just an hour will feel like you've slaved away at three hours!

Basically, I think it's dreadful to have to be in a job that you really cannot tolerate. Granted some folks have higher tolerance levels but in the long run, forcing yourself this way causes unhappiness and stresses the body too, y'know.

Overall, not healthy to the body, spirit and soul.
I think there's no harm in checking out your friend's company for a look-see and just to keep in touch with what's happening in the job market for your industry. Satisfy your curiosity, but then consider carefully if you're actually ready to leave your current job behind. You sound pretty busy, but yet quite fulfilled, in your current job and if so, you might not be prepared to make the move yet.
In any case, working at such a wide job scope in your field will be a definite asset when you finally feel ready to make a career progression move some time in future. Think of all the valuable, priceless experience you're accummulating!

I guess it boils down to you in the end. I'm just wondering, if you have to consider very hard in the first place, then maybe, you're not convinced the new job is better and / or you're not ready to quit this current job yet.
