I'm not overjoyed with the Stryker and am extremely skeptical about the degree of importance they have placed on the shoulders of this platform going into the next number of years... even before she had been fielded!
All that being said, I still much prefer the Stryker to the XM8 AGS. I see the prime bennefits of it bing much more survivable and fast. Survivability I'm sure I don't need to go into depth on but speed has proven to be an extremely important asset in almost all the conflicts since the creation of the all-volunteer army and it's battle style. It has almost double the speed of the M8 allowing it to get into trouble, out of it, and on to the next battlefield faster than the enemy can and faster than the M8 could. Decidedly important.
The other issue, and you can correct me if I am wrong, but it would have been prohibitively difficult due to wiring, free space, and power output to equip even the 1996 version of the M8 with similar modern electronics packages that the Stryker MGS has. Obviously "can do" will always allow electronics upgrades but I believe that the compromised capabilities would be less due to the fact that the system was not constructed with the idea of today's electronics in mind.