Topband: 2 Parallel Beverages

[rfman45]

 For various reasons I am considering two single, parallel but 180deg opposing direction beverages on the same supports rather than a single switchable bidirectional beverage.  The bevs would be separated by 12 to 18 inches or so. I've read that parallel bevs present performance degradation issues but has anyone had any experience with this type of setup versus the traditional bidirectional beverage? Thanks for reading this and for any thoughts you could offer.                                                                 Mike  W2LO