I just bought mine a couple months ago, the 42" fixed ones. They are fine for what I use them for and reach seems good enough where I don't see 6" making all that much difference. It's not like the 42" forks aren't long enough to lift a 48" pallet anyhow. Having longer forks seems like it's just going to make turning more difficult (and unlike a forklift, it's NOT NEARLY as manueverable).
Like Tuolomne said, when the forks are low to the ground, it's nearly impossible to see where they are and if you try to stand while moving, the operator presence switch on the seat cuts in. I know I couldn't see the tips when the forks are down and needed a spotter to guide me but this was my first time operating with them. I guess with experience, I'll have a better idea but it will always be a guess as again, unless the forks are at the widest position, you can't see them.
One issue to keep in mind that others have not mentioned: the 300cx is not a self leveling loader. You will likely be using the bucket curl/dump function often to keep the load level. During curl, you can feather the load up but the dump function is much more abrupt and the heavier the load, the more jerky/abrupt the dump action. I recently unloaded a 850 lb mower from my truck using the frontier forks and they functioned fine but I did promptly discover that the dump function doesn't operate with anywhere near as much control as the loader lowering function. 850lbs centered 30" away from the loader pins amounts to a LOT of loader observed weight.