Solona Vs SmartBCH
The major difference between Solona and sBCH network-
1) smartBCH - needs to solve tragedy of the commons, other chains hasa very good seed funding programs, an original project also takes a lot more resources to build (like enter the sphere), original projects have no incentives to build further on sBCH, because original projects also need to build a lot of unbuilt functionality, and every chain wants a "deal flow" of original projects to stand out. This goes for both sBCH infra and token projects. So good devs are basically paid to be on other chains.
2) solana is not a good developer experience, sdk is very early stages and breaks often, throughput is high, but minting costs are high vs (polygon) due to the associated tx metaplex structure. As an example, errors are often not labeled and you spend hours trying to figure out what happened.
3) a definite timeline needs to be established about features coming to sBCH, right now costs are 10x higher than the best EVM chains
4) there is insufficient guarantee or answers to questions about the decentralization of sBCH as a protocol, now I understand sBCH should not need to be BCH decentralised, but the centralised bridge and the missing details about SHA-Gate (such as how locking funds either side works) is not good. People don't want to know their BCH can be frozen or lost with a single point of failure (Coinflex).
5) on that note, solana is extremely centralised vs most other things, and the chain has failed or come to a complete stop multiple-times, it hasn't proven to be robust so far, the model may look attractive to someone unfamiliar to blockchain, but like you say it comes with it's own trade-offs, the rental model adds up and it's not as cheap as it claims.
The way Solana is designed also ensures that EVM levels of transparency is not easy, due to how its smart contracts (programs) are compiled.
6) Solana does have American institutional backing behind it, so it has very strong support and marketing for projects that launch on it + as you correctly identified, due to it not being EVM, there is far less competition.