The friends I practice with play in drop D alot. I have always played in standard tune but have no probs in drop D. What is a pain is tuning down, then later tuning up, then later tuning down.... My Foundation 5 string doesn't get much use. I like it and adjusted to the extra string in no time but I am at heart primarily a 4 string player. Now, I know there are different ways to tune a 5er. Mine is BEADG but I was thinking of making it DEADG so when we arent playing in drop D I can just ignore that string. But then I realized that with DEADG I won't have the ease of (the low D and A side by side) DADG with a 4 string . So then I was thinking DADGC. Does it really matter /how/ I have the tuning on my 5string for the group I practice with as long as it works?
Basically if you are going DADGC it's like having a four stringer in drop d with an extra string up top, in which case you might still have to change tunings if that is what you are trying to avoid. If you want that tuning cause you like your foundation 5, then that would be a good idea. Many people tune a 5'er in EADGC and that's pretty similar. Just make sure to get the right strings and adjust and necessary action and truss rod.