I'm sorry I overlooked your message. I personally was leaning towards a slightly lower hash rate for a longer period. Maybe 100-150PH until the 2-2.5BTC are spent. I have done a number of rentals with Nicehash and find that when I grab too much of the hash rate, it tends to drive the overall rental rate up to keep up that speed.
You are correct, it's usually better to rent less hashrate for longer periods, unless your rental would go into a new difficulty epoch and that could change everything, if the run starts in the next epoch which is likely going to be -10% below the current one, you will need to check the block finding pace and see if the average block time is below 10 mins, it means difficulty is likely going to spike, a 2% spike in difficulty is probably going to offset any money you saved in the rental unless you were buying a massive chunk of supply.
So really, it's not an easy pick, in some cases, going all in and renting the most you can for the shortest period is better, you can only make a calculated guess but are never guaranteed to take the right decision, which is probably why willi9974 doesn't want to decide on behalf of everyone, however, I think it's important to inform whoever is voting that the probability of finding is the same for 24 hours with 50ph and 12 hours with 100ph (with everything else being equal), when everyone understands that aspect, plus everything else mentioned in this post in regards to difficulty change, the group collectively will likely always vote for the "best".
Wish you all the best guys, by the way, what would be the lowest amount to join the run?