The reason for upgrade of a coin is to improve on it and growth and development must be a going concern. Now, as it relate to market reaction of coin upgrade, it depend on the narration and market perspective of such upgrade.
Is hard fork an upgrade to a coin? Yes, I have been into research about fork and it does compromise on upgrading coin. According to wikipedia
A hard fork is a rule change such that the software validating according to the old rules will see the blocks produced according to the new rules as invalid. In case of a hard fork, all nodes meant to work in accordance with the new rules need to upgrade their software. If one group of nodes continues to use the old software while the other nodes use the new software, a split can occur. (
https://en.wikipedia.org/wiki/Fork_(blockchain))
This is what happen to bCH and BSV. Now, the crypto has been splitting into two but BCH still has dominated over BSV as coinmarketcap.com shows the ranking list between these two crypto.
But, If I were to chose then I will go on BSV because this is the hardfork of BCH. A new and upgraded software for BCH is BSV.
Hard fork effect?
For now the effect is bad because it influences bitcoin market price drop. Sadly bitcoin market price reaches its bottom at 3.2K USD.