Planetary Geared Cranks/BB e.g. HammerSchmidt

Has any tried anything like this on a polo bike?
I'm thinking you get a pretty good ratio for polo and the ride home. Downers:

• Heavier
  
• Less reliable?
  
• Restricted to specific gearing
  
  

There's a crowdfunding drive going for some polish ones with 3 gear options and that doesn't require any specific mounting points (that's an issue with the HammerSchmidt):

http://www.bikerumor.com/2015/01/30/the-efneo-bicycle-gearbox-crank-hits-indiegogo-puts-3-speeds-up-front-and-internal/

There'll be good reasons for and against, knock yourselves out explaining them to my layman-self...

So it's a hub gear but for cranks? Bet it weighs a ton...

The hammersmith one's are pretty light... And the weight being in the middle of the bike rather than the back is a plus.

But they cost more than all my bikes put together. apparently everywhere is selling them for 1/3rd of their original price and that is less than I remember... I might get one...

I totally want one. Plus belt drive.

Exactly, I've spotted a few second hand HammerSchmidt sets going for around £150. Beats all that malarkey of taking a wheel off and having exposed teeth etc. Big problem is mountings...

Jimmy pointed out last night the problem that to clutch they need to be fairly slack in terms of engagement. Which is not a problem for other things, but not good for polo.

I totally want to build a mtb up with one though.

Or one of these, Schlumpf Speed Drive. It replaces the bb.

Got a schlumpf I am willing to sell

Which one and how much?

Mountain drive, 200£