I'm not a construction worker and I still wouldn't buy anything under 18V. I personally recently bought a very light and powerful 20V Dewalt from HD for $150 (After negotiating them down from $200) and I'm very happy with it.
I actually have an 18V myself, but I'm sure I would be fine with 14.4 as well.
My brother is in construction and for years his primary drill has been a Dewalt 14.4 (well, that and a 12V impact driver...)
Although it is also a YBMV (Your Brand May Vary)
situation. I once had a Ryobi 18V and that was noticeably less powerful than my bro's dewalt 14.4...