Differences between D2 and D3 as described in the article are easily confirmed by researching this on the internet, as I'm sure you'll agree if you do so.
d2 raises serum 25(OH)D and 1,25(OH)2D exactly the same as d3... only difference is d3 keeps serum levels elevated for 2 weeks after supplementation is stopped, wheres as d2 produces a rapid decrease.
http://www.nutraingr...-ergocalciferol
although i would recommend sticking with d3
the high calcium + D thing was discussed in the supplement forum, and generally agreed that this was probably due more to the high amounts of calcium rather than vitamin D. you cant look at a study like this that uses multiple nutrients and doesnt keep proper controls & make the assumption that it must be the vitamin D causing the problem. the proper form of supplemental calcium, adequate amounts of resistance exercise, k2, magnesium & other nutrients are needed as well to make sure calcium is deposited into bones and not into soft tissue.
there are referenced levels for serum D... most people are brought into optimal levels by 1000iu daily, as confirmed by blood tests. the key is confirming through bloodwork what amount of supplementation brings you within desires levels.
I believe you are agreeing that D3 is much more potent than D2, which was the point being made in the article.
An increasing number of experts are concerned about some negatives associated with Vitamin D supplementation at non-toxic levels, although there doesn't yet seem to be a consensus. It seems that calcium deposits on soft tissues, and problems resulting therefrom, tops this list. Although a recent study concluded such deposits in the heart don't seem to lead to increased risk of adverse incidents such as heart attacks, the Duke / UNC study regarding lesions on the brain is disturbing. I'm not sure what other studies are floating about regarding calcium deposits on soft tissue resulting from Vitamin D ingestion, as this is largely a non-issue for me.
It would seem most logical at this point to keep an open mind on this issue and consider obtaining more of your Vitamin D needs from sunlight (without burning), and less from supplementation. The best we can do is make an informed decision based on the facts available.