Are there any dire consequences being transferred over to ME3 as a result of having (or not respectively) destroyed the Collector Base at the end of ME2? What happens if a choose to preserve it?

You get tech from the human reaper, which is used for the crucible

I think you'll find a "reaper heart" if you destroy it and a "reaper brain" if you keep it.
This only affects the EMS and "ending" preference.
Brain gives more EMS than heart and makes it easier to achieve control "ending".
Heart gives a little less EMS and makes it easier to achieve destroy "ending".
And ofcourse it affects what people say to you in ME3.
So best choose according to that, what would you/your Shep do?
If you go for a completionist playthrough or use an EMS mod in ME3 you wont need those points.
You can choose between all 3 "endings" with enough EMS/Readiness.

For ex, at a very low EMS (min 1750), if you choose the blue ending and destroyed the base, Earth is devastated. But if you choose the blue ending and kept the base, Earth is only partially destroyed.
And it goes so on and so forth, having different thresholds for various choices an resulting in different measures of damage dealt to Earth. Squadmates and Shepard's fate are also affected.

Collector's Base Destroyed

0 to 1,749 EMS: Your only choice is to destroy the Reapers. Earth is destroyed.

1,750 to 1,899 EMS: Shepard can choose to destroy the Reapers, or control them. If you destroy the Reapers, Earth is destroyed in the process as well. If you control the Reapers, Earth is devastated but not destroyed.

1,900 to 2,349 EMS: Shepard can choose between destroying and controlling Reapers. Both choices save earth, and humanity survives, however Earth's buildings still get vaporized.

2,350 to 2,649 EMS: Shepard can control Reapers, and save Earth

2,650 to 2,799 EMS: Shepard can destroy Reapers, and save Earth. Shepard Dies.

2,800 to 3,999 EMS: Shepard is able to create a link between Synthetics and Organics, and Earth and the Galaxy are saved

4,000 to 4,999 EMS: You can destroy the Reapers and Earth is saved. If you shot TIM on time and saved Anderson, Shepard breathes (Survives).

5,000+ EMS: You can destroy all Reapers. Earth saved as well. Shepard will breath, whether you attempted to save Anderson or not. (Perfect Ending)

Collector's Base Remained Intact

0 to 1,749 EMS: Shepard's only choice is to destroy the Reapers. Earth is destroyed.

1,750 to 2,049 EMS: Shepard can control the Reapers or destroy them. Destroying the Reapers also destroys Earth. Controlling the Reapers damages earth but does not destroy it.

2050 to 2,349 EMS: Shepard has choice between controlling and destroying Reapers. You save Earth from destruction either way, and humans live, but Earth is still devastated and buildings vaporized.

2,350 to 2,649 EMS: Shepard can destroy the Reapers. Earth is badly damaged but isn't destroyed completely

2,650 to 2,799 EMS: Shepard can destroy the Reapers and save Earth.

2,800 to 3,999 EMS: Shepard can create the Synergy between Organics and Reapers to save Earth and the Galaxy

4,000 to 4,999 EMS: Shepard can destroy Reapers. Earth survives. If you shot The Illusive Man on time and saved Anderson, Shepard Survived.

5,000 + EMS: Shepard can destroy Reapers. Earth survives. Shepard also survives regardless if you tried to save Anderson or not. (Perfect Ending)