I recently did something similar. I got a great deal on a Gillette Slim and decided to give it a shot. I originally skipped DE and went right to straights so I thought I owed it to myself to check it out. I got a sampler from westcoastshaving and started with the Gillette 7 O'Clock yellows.
It was an amazingly easy transition for me. I had an excellent feel for it after the first pass, and had even increased from setting one to five during the pass. It seems that all the time I spent on a straight had taught me almost everything I needed about angles and prep. I used a perfect lather from some Soca Bomb (lime) followed with D.R. Harris Arlington A/S splash. I was able to complete a full three pass shave with very little irritation and without nicks or weepers.
Not the closest shave, but not bad at all for a first and definitely a dfs. I think I can officially retire the Atra Plus as my travel razor. It beat the pants off of a Mach 3 and I'm still new at it.
It was nice and all, but I still had some extra time and lather....so I went for a touch up pass with the Bismark I acquired from SRD's March Madness sale. NOW it was BBS. :)