I think the only way to play the currency futures game is with no signals - just set up mechanical entry/exit packages at the most reactive times for the currencies you are trading (at news releases, and market opening times). Trap that currency with a mechanical method when the price is at the highest probability of "reactive" quick and decisive movement - you do not need much of a price movement to make really good profits each day. Use the currencies price action against itself and take small profits several times a day on a variety of products.
Yes, less volatility, in turn due to an underlying structural reason -- high absolute correlation of the two majors corresponding to the individual currencies within each pair, e.g., EUR/USD and USD/CHF for the EUR/CHF cross. "Highly correlated, intra-European crosses" was just another way of saying "EUR/CHF, EUR/GBP, GBP/CHF."
Well, as you know, the 4-hour Momentum Tunnel Method relies on 2 specific filters. One is 100% objective, difference between the 2 weekly EMAs, etc. The other calls for interpretation of technicals (a breakout), when the 4H SMAs and the price are all within 50 pips. You could try to adapt those filters to the 1-hour time frame, if that's your preference. I have not gone in that direction at all, because, frankly, I concluded that the 1-hour Tunnel Method (a single EMA crossover, as it were) is fatally flawed at its core, to put it politely.
No, as mentioned above, I don't personally trade any of the Tunnel Methods, although have looked into them closely, as I routinely do. More than satisfied with my strategies. I am talking about the specific filters in the 4H Tunnel Method. Sounds like you haven't looked at that yet... you'll find it on the ForexFactory forum, among other places.
I don't know anything about this particular one. However my guess would be: Perhaps nobody can. Therefore the inventor needs to promote his method to everyone free, hoping to scale down a little bit of noises - one day.