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If your load is not predicted to increase A LOT in the foreseeable future, get one CCR1016-12S-1S+ with the SFP modules and see how it goes.

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It looks like there will be a number of CCRs in Bulgarian OLX soon

I don't mind getting a cheap CCR
1U server with additional NICs and RouterOS?
Is it possible to aggregate your connections on a switch, then 2x10gbit LACP to ccr1072 by VLAN?
Though you may not like the power consumption.

If I have no further upgrade path I have no choice but to consider CHR or another vendor. It turns out that I can't put 1G SFP copper modules in 1072 too...

It looks like there will be a number of CCRs in Bulgarian OLX soon

According to Mikrotik documentation, You can:

https://wiki.mikrotik.com/wiki/MikroTik ... h_1G_links
https://wiki.mikrotik.com/wiki/MikroTik ... lity_table

Unfortunately this is not a good option. The upgrade is too small and the traffic will hopefully get bigger.

It's not so small. Pure math:
CCR1009 has 9 cores 1GHz = 9GHz
CCR1016 has 16 cores 1.2GHz = 19,2GHz
(19,2 - 9) / 9 = 113% more.

What is consuming your CPU? Depending on the task of those routers, you can sometimes optimize firewall rules, decide
between connection tracking or not, queuing can also be done in different ways, and when you traffic increases you may
be able to have multiple CCR1009 alongside handling part of the traffic.
Also, instead of having a central place where
- all traffic has to pass
- all the firewalling has to take place
- all the queues have to be implemented
you may be able to have these tasks in different routers.
E.g. it does not seem to be a good idea to do the BGP (I presume internet routing, not BGP for your local network) on the
same router were you also do firewalling and queueing individually for customers.