As Jimmy said: I currently play "Killing In The Name" on BEADG five string: I don't use open D, I play fretted D. I do the same for "Slither" by Velvet Revolver. Sure, those songs might be a little easier to play on drop-D four, but they're doable on standard five.
+1 It certainly CAN be done.
But, IME, the tunes that are initially played with drop tuning lay better and sound better on the drop tuned 4 than on the 5. But, I completely agree that a talented player can get over with either one. One recent stint I did in a Modern country band was interesting, because I'm pretty sure I could tell which tunes were originally played on the 5 vs the drop tuned 4, just by the way the lines lay out.
The perfect instrument for me would be a 5 that had the Low B, but also had a drop tuner on the E. They just don't generally exist.
Some random HipShot related thoughts based on my experience:
1) I vastly prefer the way the lower notes sound on the drop tuned 4 vs on the B string. When the drop tuned 4 is in tune. Longer string length = better bass tone. But, the tuning thing is for me a bit of an issue with the HipShot. I unfortunately have a fairly keen sense of pitch; and the HipShot never quite recovers correctly, which bugs me when flipping back and forth. The biggest issue is it comes in sharp after recovering from drop, which is particularly problematic for retuning on the fly. This seems inherently due to the way the wraps on the post respond. The 5 gives the lower notes with more reliable tuning, and I like that about the 5.
2) Another issue with the HipShot is that levering the tension back and forth seems to fatigue the E string at the break point on the saddle, leading to significantly shorter string life for the E. Maybe not a big deal for some; but, with strings costing what they do, it bugs me a lot.
I still use my 4's with the HipShot for almost everything, simply because I am not gigging any situations that require the 5. But, that could easily change, if a different gig comes along. For me, the 4 vs 5 thing all boils down to what is required for the gig.