I canít say one way or another if you will see more strength gains by switching to 5x5 but there are some things that Iím sure of.
First your early gains in deadlift squat and maybe even bench press since youíve been using only DBs are going to come from neural adaptation. Itís possible that you might actually see better gains with HST since you will be doing more reps starting out with lighter weights allowing you to ďfind the groveĒ developing proper form in which case youíre neuromuscular system may adapt faster. So since youíre just starting out in the gym I would ease into allowing your body to adapt to the different exercises.
Second 5x5 will burn most people out quickly not to mention the odd are that just starting out you wonít need anywhere near that volume to hit your max strength increase potential. Something like 3x5 or Ripptoeís Starting Strength would be better for that not to mention if you watch his videos youíre going to learn how to do most exercises correctly.
If you think Starting Strength is too basic then I would recommend Wendlerís 5 3 1 since it has you cycling through intensity and volume ranges to both enhance strength and slow burnout. IMO both SS and 5 3 1 should work better and longer for strength gains than 5x5 but thatís based only on theory and not personal experience.
If your concern is that people in the gym will see you pushing light weights then suck it up. Iím powerlifting now and on speed days only do 50%-60% of my 1RMs for 3, 2, and 1 rep sets respectively on Bench, Squat and Deadlift. While it might look gay Iíll challenge anyone in the gym to do the same and not feel when they were done like theyíd been hit by a train.
Male: 51 years old
Bench Press 240 lbs. @ 178 lbs. (12 July 2012)
Power Squat 390 lbs. @ 180 lbs. (10 November 2012)
Deadlift 390 lbs. @ 180 lbs. (27 November 2012)
Total 1020 lbs. (finally made it 16 July 2012)