ARB is so awesome, I have it in my portfolio too. I also have SOL dominating in my portfolio. ALT and Manta are under monitoring, the price is good but there are many holders from the airdrop.
You have little bit diversified your portfolio but I think you should also hold manta because it is going to increase very soon and still it is a successful coin as many individuals have earned it through Airdrop. Arbitrum and Solana are your wise choice as now both of them are going with great achievements but if there is some dump during certain timing then it should not be a matter to be worried because all these are a part of crypto industry.
SOL momentum is quite easy to understand for those who want to gain profits in a short time. I have benefited several times from SOL. no need to hold on too long, that's what I do. although from the perspective of investors, there must be some who will hold it for a very long time. because market growth and adoption of the Solana network are growing rapidly.
The better way to take benefit from Solana is to buy at dip and sell when there occurs pump because Solana is more volatile coin and very easily it is changing from lower to higher and from higher to lower. BUYING of Solana for lengthy time will reduces your profit therefore concentrate on your profit and continue the process of buying and selling because with a single decision we cannot make profit but we have to change our mind according to market situations.