I just purchased a brick(12) of the Tally-Ho Fan Backs about a month ago from Theory11.com. I could not be happier with the cards and the level of support I have received from this magical community. Here is a small token of my appreciation.
Wow, I didn't even know these could be marked...Although looking at the back design again I kind of have an idea of how it could be done. I know that the Circle Backs which I also got a brick of, are one-way backs very subtle with the gap on the pedals of the flower. I still am plugging away at the bottom deal. I think I am getting decent with the Erdnase Grip, do you think it's time to move on to a different grip or just become more comfortable with the Erdnase? I mention this because in The Expert at the Card Table one line reads "The art of card palming can be brought to a degree of perfection that borders on the wonderful." I think this is a statement that should be applicable to all moves..Good to hear from you Jason, hope all is well.
P.S. Looking at your videos , I know I still have a lot more roads to travel before arriving at my destination.
Every deck can be marked. All of them. No exceptions.
With regard to the bottom deal question - do what makes you happy. If you like to experiment, then by all means do so. If you like to perfect a given technique or sleight before moving on, then do that. Whatever works for you.
I don't have the answers; I just encourage the asking of the correct questions.