MRC's, Becketts and Aqua C's are all versions of eduction type skimmers, using high pressure and high flow to aerate water. Reliable, and simple but can be noisy, use big power hungry pumps, and work best when they have large/huge/tall reaction towers to allow sufficient contact time despite the high flow rates. If your system is large enough that you need multiple needle wheels the power use may be worth it esp. if you have a fish room or basement sump to house one.
The various needle wheels are owning the market now for good reason...efficient power use, quiet, space saving, love my Vertex IN250's bang for the buck but when the original pump is done a bubble blaster would be the replacement of choice.
Don't look at gallon ratings too much...compare air draw and chamber volume...there are no magic shapes either...cones don't make skimmers more efficient, but do make them more flexible re: matching size to system. Specifically allows an"oversize skimmer" to maintain a stable foam head in a smaller than capacity environment but does not increase the maximum capacity.
it looks pretty bad now that I look back at it 