:'(
What you need to remember is that a real-life performance actually allows you to get away with lots of stuff. If I am alert, sometimes I manage to ''control'' a card just by placing it on the top, and NO ONE SEES IT. With that in mind, I guess both would be equally okay with good crowd management skills. However, to handle the 'burner' kind of spectator, you might want to use one with a border. Makes the whole process simpler.
I feel that only strive for what is essential...just like I feel that you should only strive for a Xavior Spade Level Classic Pass only if you want to perform it as something like a stand-alone effect, otherwise it makes no sense to spend months on it when in real life presentation is just more important. So don't be too worried about mastering the DL with a borderless deck. It:-
1)Doesn't make sense.
2)Most borrowed decks will have borders.
So I guess, work on the effect you wanna do with the DL than the DL itself