Don't do it. It's simply not safe and the end result will be poor.

Can you show the needle/foot you use? I am now confused because the foot provided with my Janome 6500 sounds like the one you say isn't right.

honestly, this is the way we did it in the 70s and 80s when everything was done by moving the material... no machines with built in embroidery... the closest they came was the rudimentary line stitching with arrows, hearts, flowers, etc..... and by the 90s, we had a few alphabets built in... I took machine embroidery in adult night school. We were taught thread painting, applique, satin stitching (which is the ONLY thing we did with a foot on, and 'writing'.... it not only can be done but is done all the time.....and in every class, there was at least one person who forgot to put their presser foot down for a minute... you know immediately, because it doesn't want to sew... presser foot down and go..... single line quilting is much easier than some of the techniques we were taught...

I've seen some quilters (Leah Day, for one) "modify" their FMQ foot (like the one above) by cutting out the front third of the oval for better visibility. I also have a metal FMQ (janome) that is made with a gap in the front part of the oval (so it is open). I have seen videos of it being done with no foot at all, but haven't tried it myself. I'd say take it for a try and see how you do.

Here's the video of how Leah modifies the generic FMQ foot. The part where she clips the plastic oval begins at about 4:50 into the video, althoug it's worth it to watch the whole thing. :)

http://www.daystyledesigns.com/freemotionfoot.htm

http://www.daystyledesigns.com/freemotionfoot.htm

Here's Leah's modification - the part where she clips it starts at abotu 4:50 into the video.

I don't know the advantage of the metal feet - although that's what I use. Mine is actually shaped like a curcle with the opening to the front. I have used the generic hopping feet too, although that was before I learned the nice modifications.