So, I've created for myself brief checklist which helps me to make this non-easy decision.
- How long it will take for me to master the major approaches of selected technology?
- Can I reuse the gained knowledge during my daily development work?
- How long it will take to train/coach my team mates to use this technology?
- How big is the market for the selected technology?
- How big is the local community for the selected technology?
- How easily can we hire new developers with appropriate knowledge in selected technology?
- Will it be profitable to have the knowledge in that technology?
I know that some items are very boring and mercantile, but it's life, real life. And we should align our priorities appropriately.