Ralph,
Are the VHO's still on? You can drop them. With that length of tank you would of either had to go with 3-400's 20K, 3-250 10K and VHO actinics or what you did. Since you already had 4 MH's that was your best way out. I ran just 20K XDE bulbs and I was not happy with them.
From what I have read, the CV's burn whiter. IMO you need the 2 (the 2nd and 4th bulb) to burn bluer. Like a Radium. To me, the XDE was dim. I am not familiar with the 250 Radium but in this case with your 10Ks the dimmer and bluer 2 should help. Leave the VHO's for maintainance.
BTW, your tank looks nice.