Hi Bee
Looks like you've done some of the research yourself already and have narrowed it down.
The first thing I'd recommend is that you do some searches on candlepowerforums.com (CPF).
It's a great online community, similar to ETS in that there's a lot of knowledgable folks very willing to share what they know, and very civilized in th eway they treat each other.
I'm unfamiliar with the NiteIze upgrade, and the description I read on the NiteIze site doesn't say if it's regulated or not, but it is physically similar to the Opalec module, which I have owned in the past. The Opalec IS regulated - 10 hours of consistent light output.
That's what I liked about the Opalec, and it has an even, more floodlike beam than the standard bulb of a Minimag. However, you can't adust it to focus or widen the beam. The standard bulb and adjustable reflector will allow you to shoot a beam farther than the Opalec can.
One vendor that has both of these upgrades is
Brightguy -- I have personally had good experiences with them as a vendor, for what it's worth.
Most LED replacements are a compromise - battery life vs. output vs. price. My personal favorite is the MJLED (however, it's unregulated) - you'll have to search on CPF to find links to it and where to buy them. They have been in short supply recently - hopefully more wil be available soon.
The light output of the MJLED is a bit more than the standard bulb produces, battery life is said to be 20+ hours on alkalines and 35 hours with lithium AAs, and the price is about $5 each, or about $10 to get a full kit with a reflector that has been drilled out (the LED is wider than the standard bulb).
However, it's very easy to drill out the reflector, and all that needs done for the LED is to trim the leads.
That said, there are several other sources on CPF for different versions of LED replacements, among them the "Sandwich Shoppe" and
www.led-replacement.com. Good luck
Dave