Combing two networks - two ospf areas, or two ospf processes

We have 300 switches (3560, 2960XR, 9300) and about 900 IPv4 routes in TCAM. The New network has about 100 switches (Linux boxes running bird and a dozen 7050 arista) and 200 routes.

Both are area 0, and combining them would be hitting some TCAM limits on the weaker switches.

We started converting the new network to area 20 (and plan on going back and changing original a network to area 10 and leave two switches as ABRs in area 0).

Does anyone ever just leave the two networks in separate area 0s and then have two ospf processes on the routers that touch both? Seems like that may be less work... wonder what I’m missing in terms of long term stability.