While it may be dangerous to experiment with LRs, unless the immediate result permanently cripples the magus/his subject or outright kills him, Core states in Experimenting with Longevity Rituals "If your ritual is flawed by a roll on the Extraordinary Results chart, you may create a second ritual, which over-rides the effects of the flawed ritual, but this takes an additional season."
So a do-over is part of the process, if the magus so chooses, which tends to lower the danger level considerably; of course, losing vis and a season are not fun, but experimenting on some random grog is an integral part of expanding Hermetic Theory! Aurulentus pursued his dream, some accidents are bound to occur, but they are learning opportunities...for the Magus. Happy accidents! For Magic™!
*edited: I find studying the Bronze Cord, indeed the Familiar bond itself much more dangerous. It's unlikely the Magus will be studying someone else's Cord, so would have to Experiment on his own. There are no do-overs provided in that section.