I own an Arrow IV (the T-Tail one) having trained on Warriors.
Some things possibly worth mentioning to look out for in an Arrow to avoid unnecessary panic - mostly common to all Piper retractables I am told (and often not mentioned by instructors!):
Gear unsafe light coming on in-flight (as opposed to not going off on retract). This is not a great problem - if you don't like it, slow down a bit and cycle the gear and it should go out. If it does come on it is probably caused by the gear sagging slightly after some time or having been shaken down a little by turbulence. There are lengthy discussions about this on the piper owners' club forum (
www.piperowner.org).
Lack of any green lights on gear extension - the panel lights are probably on. If the panel lights are on then you will not be able to see the gear lights in daylight - period! Watch out for instructors who like to flick the panel lights on while you're not looking!!! At night by the way they are perfectly clear.
One light not coming on on gear extension. Don't panic yet! Place a finger on each light and press it. Quite often one will have joggled loose. If this doesn't work - take out the one that is not lit, then take out one of the lit ones and put it where the unlit one was. If it lights up.... all is well! Otherwise.... land gently somewhere that is open so that they have somebody around to remove the aircraft from the runway! A gear up landing is unlikely to hurt you if you can avoid panicking, but you will require assistance at that point! Incidentally, I read somewhere that a tower flypast is just a waste of time! What are you going to do when that one light is out and the guy says it looks like the wheel is down?? Is he sure of that??? Aren't you going to land as though you expect it to collapse anyway??
None of the above are particularly common by the way - but they do happen and can give you quite a start! I've had them all happen once or twice in about 100 hours in the Arrow.
On the large tank thing.... I have the 77 USG tanks. If you fill them up and put two fairly normal size people in the front, then your C of G will probably be forward of the limit. Given that the Arrow is already fairly hefty to flare, trying to land in this condition will probably bring the nose down quite hard, although keeping power on all the way to the ground can reduce this to manageable proportions.
I've not flown one of the straight tail Arrows so I don't know how they differ. The T-Tail though does not glide terribly well with the gear down so it's worth doing a few glide approaches with an instructor. My first two attempts were woefully short of the runway!
A particularly good power setting I find by the way seems to be to select 2100 RPM and then whatever MP you need at your height to give you 65% power. The fuel flow drops right down but the speed will only drop to about 120 knots - on mine at least. It's quite quiet at this setting as well.