I personally favour the quint layout which has the overriding advantage that the same notes are to a large extent overlaid across the both stradella and FB on a converter. In all music and particularly classical genres, the LH should be a combination of bass notes and harmony triads. The quint converter enables switching between the 2 modes during a particular piece even for a couple of bars, enabling seamless deployment of both single note runs and chords. With the chromatic FB systems either the European or upside down Russian there is an awkward relocation of the LH, such that on my c-system, I have to use either FB or stradella in a given piece; can't cope with both as relocation introduces another potential inaccuracy, though that may be overcome by a few 000 hours of practise. For me I think not using both phases on the fly throws away a versatility and attraction of the converter. Regarding the range, amongst my menagerie of instruments, I have a 160 bass quint which has the potential for 4 octaves (actually more than the 45 note RH on this instrument). However I've never seen a Roland with a 160 bass so accept the point about fewer notes, though having the option of more duplicates in a logical musical layout in 4ths and 5ths is a compensation especially changing keys. Another eponymous label for quints is "GR" applied by the Petosa brand made by Zero Sette, now incorporated into Bugari. This is a nod to Anthony Galla Rini, the late American celebrity accordionist and exponent of the quint who, similar to Palmer, likely had a marketing connection with some of the US distributors. In the search for the holy grail, I've handled several systems but on balance by far the most useful, comfortable and for me most effective, versatile and therefore most rewarding musically is the quint converter PA (even though I'm not American).