Only thing I have heard of is bad strings on the Mathews. The Mathews forum is ripe with string issues. Cracked limbs seems to be the vogue net gripe with most bows these days. I quit reading about cracked bowtech limbs a long time ago and just enjoyed shooting my bow (and great factory string btw).

Drenalin limbs are small profile so I imagine you must be careful with them (no dry fire, etc.) but I don't have any real worries about them as I didn't plan on dry firing the bow anyway. I worry more about splintered carbon arrows these days.