Interesting discussion. I have experience from the other side of the fence in that I am a signal provider on ZuluTrade and formerly on Collective2 :-
http://www.zulutrade.com/TradeHistoryIndividual.aspx?pid=20470
I've spent a couple of years developing a generic EA that runs on MetaTrader using trading rules found through a separate AI type engine. I run this now on a demo account and feed signals into ZuluTrade. I also ran it on my live account but switched it off in December as it was suffering from heavy drawdowns. It's looking a little better now and I'm contemplating switching the live account back on and I'm also nearly ready with another set of signals for a different currency pair which should help diversify the risk.
I run the system on a demo account rather than a live account so that I can track each system independantly and then decide which to use on my live account. My live account is not linked through ZT as I want to avoid the increased spread involved and I need access to my account balance.
I did have a handful of live subscribers when the system was going well and the system got up to around #60 in the rankings, but, understandably, my subscribers deserted me once I encountered the drawdowns.
Generally I have found ZuluTrade very reliable in that it has never missed a signal and it accurately tracks wins and losses but I do have a few issues :-
1. Subscribers often way oversize their trades from your signals. My position sizing is based on 5% of the account size which controls risk and means that it is impossible to wipe out your account. Typically on a $500 account this would mean a size of 0.01 or 0.02 lots. I found that subscribers were regularly using position sizes of 0.1 lots which meant the losers were taking huge bites out of their accounts. Unfortunately as a provider, you have no control over the sizing and no access to their balance in order to size appropriately. Position sizing policies need to be clearly stated and enforced or at least recommended to the subscribers.
2. ZuluTrade has poor statistics which makes it very easy for the providers to 'game' the system to get high rankings and attract more subscribers. I was surprised to see many providers with a 100% win rate but when I looked more closely, I found out why. It seems that many unscrupulous providers never close a losing trade and instead just leave it open until one day it turns green. This means that slowly they accumulate more and more losing positions until eventually they'll get closed out by their broker and they will be blown. They must avoid this by constantly topping up their accounts but punters won't see this and instead only see the great stats. If the providers get enough subscriptions, they could maintain this charade for a long time. If punters follow one of these strategies they will certainly lose because over time they will rack up enough open losers to eat up all of their margin and then, bang, they'll be closed out and the account will be blown. There are also plenty of systems using Martingale sizing that should also be avoided. ZuluTrade needs statistics that includes open positions in the overall p/l and also use something like Sharpe or Sortino ratios to ensure that profitability is sustained and not just a flash in the pan.
Good luck with your search but please be very careful when choosing providers on ZuluTrade, my recommendations would be :-
1. Don't use any with a win rate over 80% - it can't be true, check how many open positions they have in the same asset. The best systems should only have one position open at a time.
2. Check for Martingale, by looking to see if position sizes increase after a loss. Typically on the equity graph, you'll see deep cuts for losses followed by instant repair on the next trade - avoid,
3. Avoid scalpers with many small wins of a couple of pips each. These are unlikely to be profitable by the time you've taken the increased Zulutrade spread and slippage into account.
Following these rules, you'll be on to the second page of systems before you find anything interesting.