I can only give you my Radion experience, and I will try to not be biased vs the MM units, because I have seen nice pics of SPS under them. I have six Radions over my 300 gallon, and two Radions over my 100 gallon.
Radions:
Positives:
1. highly programmable- dial in whatever Kelvin you want, simulate clouds or thunderstorms, they work in concert with Vortech Pumps. They come with a Programming Utility that is user friendly. Program a sunrise/sunset passing over your reef. Every LED color is individually programmable.
2. Customer Service-EcoTech CS is second to none. Got a problem, help is a phone call away.
3. Customer Forum on the Ecotech website. Get help from fellow Radion Users online at a couple different locations, the EcoTech Forum or the Reef Central Sponsor form.
4. Upgradable- Radions can be upgraded as LED technology advances.
5. These grow SPS at the bottom of a 28" deep tank.
Negatives;
1. High Price- My personal opinion on this is that EcoTech is excelling as a small company with a highly defined product pallet and very limited marketplace, and their prices will be higher than similar products like the MM units, that come from a Chinese Company that also makes large quantities of hydroponic LEDs and LEDs for other industry applications, with the corresponding cost savings these Economies of Scale will allow. I feel the above positives absolutely outweigh the Radion's higher price point, just personal opinion. Their (EcoTech's) operating costs will also be higher since they are an American company, even though the origins of their product may be Asian. Also, EcoTech operates through a network of LFS retailers, and is not selling directly to the Public, as is the MM manufacturer. The MM manufacturer is bypassing an entire layer of distribution and resulting increase in pricing that way. Not necessarily a bad thing, but just a fact compared to the price point of these MM units.
2. No Mac based Programing Utility (yet). This has been a problem for some potential Buyers of Radions, as Mac Users have grumbled about it. They are working on it, and will have Mac based Programing available in a future update, per EcoTech.
3. Programing can be fiddly. The EcoTech configuration utility is a work in progress, and could be a PIA when it was first released, although several software updates have addressed initial problems with the Utility.
Member Modified Units: No personal experience here, so take this for what it is worth.
Positives:
1. High Par.
2. Grows nice looking SPS-seen pics.
3. Lower price point than Radions..
4. Buyer customizable- add UV or different LED colors, ratios of blue/white, etc.
Possible Negatives:
1. Does not have anywhere near the Radion's level of programability.
2. Dimmable or fixed output only. There is a dimmable and non-dimmable version, I think.
2. Quality issues and subsequent Customer Service? I don't know what the quality of these units is, but if there is an issue, you have to get replacements or service from China, I think. MM owners can correct me if I am wrong here.