Upon reading all the positive reviews on the forums here, I decided to try the magnum M5 for myself.  I am tremendously impressed with the razor.  the feel of the steel handle, the close smooth shave, and, of course, the price!!  Yesterday, I was doing my normal shave in the shower.  The razor slipped out of my hand and the single trimming blade gouged into the top of my head!!  OUCH!!!!!  It left a perfect little flap, the exact length of the blade itself.  When it first happened, I didn't move, I hoped it just bumped my head.  Then, the blood started running down my head and down my chest.  The funny thing is, when I TRY to use the trimming blade, I can't seem to get the right angle to get it to cut closely. Maybe I shoud just throw it at my sideburns and see how it works!     I know we all are always using care when shaving our domes, but this just shows again, it only takes a little slip for a couple days healing before you can shave again!!  I was going to post a pic, but didn't want to offend those with sensitive stomachs!!
Jim.

Don't worry Jim, I did the same thing to my ear.

Thanks for the tip buddha, I will give it a shot. 

I'm having trouble with the trimmer also.

Yup, I was moving the razor behind my ear and made a nice cut in it with that trimmer... I knew if I cut myself that it'd be around the ears and thought I was being careful.  One of the blessings of getting old I guess, loss of depth perception! 

Yeah, the trimmer blade is the single negative thing for me about that cartridge/razor.

I've learned to either keep the razor close to the skin on the back stroke where it can't catch and dig in, or far enough away from the skin where it doesn't come near.

There is no pleasant in between for that little SOB.

It can definitely take an interesting slice out when given the opportunity.

Wrote them a note about the same thing and this was their response:
 Mr. Jones
 
Thank you for the feedback regaarding our M5 Magnum razor and the trimmer blade; everyone here at Personna American Safety Razor  understands that Customer satisfaction has to be our first priority.
 
Due to Customer comments that we have received through email and ourt toll free line, we are in the process of making a modification to the trimmer blade on the M5 Magnum cartridge. Production is tentatively scheduled to begin in November of 2009. If you are interested in receiving samples of the cartridge with the revised trimmer design, we can send you complimentary samples to the address you provided below, once they become available.

 Again, thank you for taking the time to contact us.  If I can be of further assistance, please do not hesitate to contact me.  We always appreciate the opportunity to serve our customers.