The economics of it all are interesting. It would matter what the specs and costs are for that 250AH BB compared with their 100.
Say that Relion 300AH is limited to 100 amps and you need 130 amps. The cost is about $1,000 per 100AH.
To get the extra 30 amps you would need two of those 300 8Ds for another $3,000. $6,000 for 130 amps!
So if you went with 100AH batts that can do say 50 amps each and got three, you spent the $3,000 and get 150 amps.
If two 100s can't quite do the job you want so you need a third, will a 250 do it for less cost than three 100s? Can you get the extra 30 amps with an extra 50AH or do you need an extra 100 so the 250 won't do?
It can come out to anything, depending on the actual specs and costs, but does show, as was mentioned, that you really need to check those specs and costs to compare with your planned use.