Whenever I see a Stripology thread, I always debate with myself whether or not I should post because I love mine so much, but I don't know if it's simply one of those love it/hate it type things.
I use a 45mm fiskars cutter and have never had a problem moving the blade up the slot, but I always start in the wedge in the bottom and make sure I'm actually in the slot before starting. I can feel if it's in the slot or not, and cutting with the ruler is just so ridiculous fast for me that I really don't see the point in purchasing a die cutter right now. I can cut a jelly roll in under an hour, including ironing time!
I also always place my hand (carefully!) over the next slot over to the left, to make sure I'm holding the ruler down firmly. Are you having a problem with the ruler sliding, or is it purely getting the cutter to move up the slot? CG has the wonderful grippy stuff on the back so my ruler hardly ever moves - just once in a while when I'm cutting on the trim up line on the left that isn't really holding anything down.
I bit off more than I can chew again this year for christmas, and got a super good deal on a couple very easy panel kits that I wanted to make for my little ones. Very easy - panel and strips, and I was able to iron and cut the entire top in well under an hour using my Stripology. I timed it because I love the ruler and I'm always excited to use it
Very sorry that hasn't been your experience!