I don't intend to get into a discussion about which tank is better etc etc but in the interests of balance I thought I might add my experiences with the SP-445 tank which I have had since just after they first came out - I ordered it from the States.
1) After a few dummy daylight runs loading the film holders and then loading them into the tank, my arthritic septuagenian fingers have had no problems with either process in the hundreds of times I have used them, but of course people have different levels of manual dexterity so that's probably not significant.
2) The first films I developed exhibited the characteristic marks caused by the moulding flash on the film retaining tabs but a few minutes vigorous re-profiling them with fine abrasive paper removed the problem and I have never had any marks since. I have to agree with others that this should not have been necessary in a properly QA'd product.
3) I have never had any liquid leaks using the "squeeze play" method that Alan refers to but I I use a tip given to me years ago when fitting anything which has an O-ring seal like the tank lid - moisten it before fitting. I simply wet a finger tip and run it around the ring before pressing the cap squarely into place. After doint the 'squeeze' the tank sides should remain indented, if not then there is a bad seal - repeat the process and try again. If it still doesn't work then either the O-ring is worn/damaged or the tank is distorted.
4) My film holders are the V2 ones I believe and I have never had any of the reported 'shadows' or other uneven development (although I can reproduce them fairly predictably simply by loading the sheets emulsion side in), however, the company is being responsible in that they have responded to customer complaints by producing different variants. As I understand it there had never been an 'acceptable' cause or reason why these 'shadows' have occurred so it remains to be seen if the latest 'textured' varient has any reported beneficial effect.
5) I use a two-axis looped inversion technique rather than just spinning it around it axis as shown in one of the instruction videos. I believe this ensures fairly active and efficient movement of the liquid in the tank.
6) Regarding the stability of the narrow base, what can I say is that I haven't had a problem, perhaps that is because between inversions I stand the tank between the stop and fix bottles in my tempered water bath.
So, for what it's worth, this is is my two pennyworth (or two cents worth for those across the pond), perhaps someone will glean something useful from it.