I tend to keep a healthy/reasonable focus on the vulnerabilities (I didn’t say “weaknesses”). It should be a “healthy low stressor” —

1. f you care too much about them, they become distractions during travel. You end up worrying about them when you already have too many things to worry about.
2. if you don’t care or don’t know the vulnerabilities, then they tend to fail earlier and fail at the worst time during travel

Q (open): how do we assess wheels and handles when buying luggage?

— #1 vulnerability .. wheels

Q (open): Is there any form of backup/spare while en-route?
A: carry spare wheels (screw-on) + screw driver
A: I suspect that many travelers simply buy a new cheap one en-route. Price is more inflated if you are more desperate (demand) or (supply) choices are  limited.

• Tip: external wheelers .. use wheeled carts whenever available, to reduce wear-n-tear on my luggage wheels.
• Tip: load balancing .. Given four wheels (with the two handle-side wheels being less optional), I often spread the load to all four wheels
• Tip: bumpy path .. when load is heavy and path uneven (very common), the wheels would endure heavy wear-n-tear. I often lift the luggage to relieve the wheels.
• Tip: excessive load .. in one luggage bag is hazardous. Better spread out the heavy load. I often put heaviest items[water, metal, books] in backpacks, just to spare the wheels.

— #2 vulnerability … retractable handle.

Luckily, if broken, we still can rely on the short handle as a kind of backup

Interesting fact — the left-most base keys reproduce the same rumbling sound of an acoustic piano. However, I hope brilliance can be adjusted.

— Top 4 brands: Yamaha; Korg; Roland; Casio
I tend to associate Yamaha with expertise in acoustic, but Roland and other brands could be better.

Pearl River, the biggest piano factory, makes both acoustic and digital pianos.

— advantages over acoustic piano

• portable. Can remove the stand and further reduce the weight. at least 10kg
• .. some can run on battery for 13 hours
• ambiance and brilliance adjustment
• touch sensitivity adjustment? Not widely available.
• recording
• metronome
• no tuning or heater required
• variety of timbres can be simulated. The sound board is the most expensive and most important piano component responsible for sound quality.
• night-n-day feature: volume control with earphone.
• .. Paradoxically, this would remove the motivation to seize the moment and make best of the window of practice. 买书不如借书。

— my requirements

• weighted keys and finger touch, so you can strike harder to produce a bigger sound. In 2010, many sub-$1k models feature weighted keys. I believe these are electronic imitations of mechanical key.  Lots of details in https://www.yamaha.com/en/musical_instrument_guide/piano/selection/selection002.html
• eg: Casio CDP-S90 recommended — https://music.casio.co.uk/blog/weighted-piano-keys-why-they-are-important-for-a-beginner has details
• eg: Korg B2SP “88-Key Weighted Hammer-Action Keyboard (Natural Weighted Hammer Action)”

Some models require a minimum force in order to produce a sound. I thought it was inferior design, but now I think acoustic keys also have the same “problem”. In that case, it’s a feature not a bug. If your model requires no minimum force to produce a sound, then it’s more like a portable keyboard, and won’t help you develop the right touch.

Based on my requirements, our existing piano and my usage (very low), my budget is below $1k. Probably the lower the better.

—  some final shopping tips
First time, buy a low-cost until you know what is more suitable. However, digital piano costs more than phones or laptops.

If you are particular about touch sensitivity, then better compare with an acoustic “touch” immediately. You can detect the differences only if you compare immediately. Don’t compare with your home piano, because not all acoustic pianos have the same touch.

http://www.hostelbookers.com/search/city/93/arr/2017-01-31/ngt/9/ppl/2/

airbnb also has good listings.

Used to be 4 times a year. How about 3 times a year? one week+ each time.

Pick the bench time? Plan ahead.

December furlough (fur on lower belly)? Find out in advance and plan ahead.

LG – Pick low-fare seasons? Worthwhile if saving $500.