I have never owned a F75 but i do own a T2 and its still the original one,the boost mode in theory is a good idea but is only really any good for pinpointing a deeper target rather than running in boost mode all the time,the signal is not as clear as normal its more grainy as i call it.You dont mention if you would be using it just with the stock coil or even what type of ground conditions.Using a detector with a boost mode and calling yourself a 'cache hunter' is very vague,you do mention that you will be looking for 'cache hoards' 98% of the time then prehaps another more specialized machine may be the better route to go down.
Are you looking for a special 'cache' in particular or just hoping of finding one as a result of using a slightly deeper detector ?? to increase the chances of finding one its worth doing plenty of research into say things like location,asking local folks about the potential of such a find being in the area,then of course the detector is a very important part of making it all worth while.Just buy buying a detector with a 'boost' mode does not mean you will find these 'big payday' finds.
If i pick up on the trail of a possible hoard site here in the UK,the 1st initial suggestion of such a hoard in the area is when you start finding a few scattered coins in a tight radius this usually is because a plough has gone deeper than before and taken the top of a pot that has possibly been in the ground for a few thousand year,as a general rule pot hoards or infact they could be in leather or even iron container are in the 15''-24'' depth range,a normal T2 with a large coil will do for most needs,but i also do use either a Pulse machine or a couple of Nexus machine that the T2 wont reach depth wise.But before i start digging deep i have to bring into account my 'reward to effort' ratio as shifting alot of soil can be back breaking work for little returns on the effort.
We are lucky here in the UK that mamny many hoard are still awaiting to be found.