I have always used 1 pc tactical bases. I like the option of ring placement it gives you. With a 2pc base your kinds stuck mounting the scope where they want you to. A 1pc base lets you play with the mounting to tailor it to fit you needs.
I prefer a 2pc base as it gives easier access to the feed area,particularly when dealing with ammo problems in a blind magazine bolt action. Wider 1 piece rails make this a bit more difficult for my stubby fingers.
That said, the mounting/bedding and proper securing of the base screws is the most important part. I watched a nice EGW 20MOA mount come completely loose on a rifle at the range last time I went.
I prefer a 1-piece base on my 300 RUM because it also acts as a brace for the receiver adding strength and making it more robust on a receiver that takes a pounding from such a large magnum cartridge. By making the receiver stronger, it is my understanding that you will see less shock and flex transfered to the optic mount on it.
Anyone with experience with the Talley lightweight one-piece with integral scope rings? Outside lack of adjustment for length of scope, they seem like they should work well. Many have used the individual lightweight rings alone and this just adds the one piece base for good alignment.
The Talley 1piece ring/mounts are what I was using before o made the switch. The problem I had was I couldn't get them to hold my scope without it shifting under the heavy recoil of my 300rum pushing 210gr vld's at 3200fps. Even at 85 In/lbs.
I always use the one piece bases on my long range guns. First you need to pick a quality one piece base (mine are nightforce). I have looked at cheaper so called "tactical" bases that have not been straight. Next bed that 1pc base to your receiver (I use devcon), this allows the base a stress free position. Now you have the strongest most stable mounting platform anywhere.