I can see this thread heading south, as was probably Donny's perhaps unconscious intention (when has this issue EVER stayed polite? - it's been hashed out enough times!), but I guess the deeper issue is, what SOUND are you willing to put up with?

There are those that are happy enough with MOTL arrangers, and there's nothing wrong with that, but it's undeniable that TOTL arrangers sound better (or they wouldn't sell any at all!) and tend to weigh more. Plus, there are those that playing FULL (or close to it) piano parts are part of their 'style', and an arranger with a 76 is part of what is needed, and once again, that adds weight.

Life is full of compromises, and sadly, keeping your gear light involves making them... Some of us are willing to do that, some of us aren't.

Mind you, is there a thing as 'TOO light'? Personally, I've played some of the VERY lightweight keyboards, and a major problem is keeping them in one place while you play! Put them on an X-stand, play heavily at the top end, and they go flying off the stand (or at least bouncing around like a gymnast!). You can't play well under those circumstances... A keyboard MUST remain static while you play... you get an ultra lightweight keyboard, you end up negating the weight loss by having to haul a heavy table around to give it some stability.

Bottom line is, I look back to the days when I hauled around a B3, Rhodes Suitcase, CP70 and a big Leslie (amongst other things), and all of a sudden, 45lbs. total doesn't seem like such a problem! Especially when that 45 lbs. gives me a sound close to indistinguishable from the old heavy gear! Until they bring out a lightweight arranger that doesn't have a lightweight (comparatively) sound, I'm going to stick to what sounds best... And thank my lucky stars the B3 stays in the studio, now!
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An arranger is just a tool. What matters is what you build with it..!