Does this coin have strong enough technological value to keep growing, [...]?
I'm observing Byteball and have read the whitepaper. I'm not sure if the DAG has any advantage over a traditional blockchain besides faster transaction propagation, so that could be a plus.
But on the other hand, the coin is actually very centralized (it can be regarded as a "proof of concept" at most) and not totally trustless, even when the witnesses are to be freely elected it will be more a kind of "web of trust" like Ripple. I regard it as more centralized - and thus more vulnerable to social engineering attacks - than DPOS coins like Bitshares.
Did you read the whitepaper?
Note that just because you regard something as centralized does not make it centralized. Being anonymous and being decentralized are two different things, the fact that witnesses in the Byteball network are known entities is an advantage, not a disadvantage. It would be very difficult (read effectively impossible due to the negative return on investment) for someone to acquire enough witnesses using fake identities to create a "shadow chain" that the main chain would not deem invalid.
The system is a democratic one and will require some vigilance on the part of its users to maintain honest witnesses, however if you have people using Byteball for storing or transferring any substantial value then they will ultimately be very interested in the health of the network.
Scaling is the biggest issue for crypto currencies and if any store of value wants to really take a global stage it has to be able to deal with the demands of that. As soon as transactions start slowing down you hamper productivity - people will move to a faster chain. Maybe Bitcoin will retain its value because it was #firstcoin and but it cannot handle the demands of hundreds of thousands of transactions per second, which is what you will need if you have a platform that deals with trading digital assets. This is why, IMO, I don't think Ethereum has a future.
my $0.02