XA.S is the first to point out that my proposed upgrade to a 4-room flat in the same block is a minor upgrade. Now I recognize it as a SlightlyBetterHome:

• same rental amount
• same size
• same location in every aspect
• similar age

Q: Why is SBH a potential problem?
A1: we are striking a balance:

1. If I spend “too little” on this SBH, I am fine as a minimalist, but not my better half. I often feel I have “too much” spare cash, not giving her enough quality life. She sacrificed a lot for the family and deserves a more comfortable, more modern home. She deserves splurge.
2. If we overspend then ROI is too low. ROI in terms of rental yield or appreciation. In this case, ROI is low but not as low as a bigger upgrade. I do foresee a loss of rental yield. It hurts my self-esteem because subconsciously, I want every dollar to work hard and generate returns.

If we look at maximizing ROI, my wife and I are very different personalities. For me, ROI means rental yield (or appreciation), so $0 spending is maximal ROI. For wife, low-floor living is becoming intolerable, so some amount of investment even without rental increase is a good ROI.

A2: Since late 2019, we have enjoyed a cash flow high ground…

1. If I overspend on this SBH, I give up a lot of high ground. In this case, the loss is tolerable. Am reluctant not resentful about it.
2. If I spend “too little”, the home improvement is too much hassle about nothing. In this case, it’s mostly higher floor + better renovation… non-trivial improvements for wife.