While good quarter inch seams are always desired (in order to have good star points, etc) I think that being consistent in all seams is even better..if your seam is more like three eighths of an inch than a quarter, but it's consistent throughout the project, crossing seams should still line up correctly...again, this philosophy will not work with patterns that have points in it, since cutting instructions are designed for that "perfect" quarter inch...having a quarter inch foot helps me be accurate AND consistent.
and I support the variegated thread suggestions.