Simple answer is no.
Regardless of play style, Cid does not contribute to DPS, nor does Cid receive multiplier bonuses to any of his natural abilities at level 200-4100 which the others do (between 4x and 10x at 25 level increments). This makes leveling Cid mostly about unlocking his early boost to click damage. On about your 10th ascension and thereafter, you're unlikely to find even this click damage to be particularly useful; it would constitute less than 1% of the over all click damage from a roster of heroes generating DPS and a percent of DPS as click damage.
When playing idly it is important to note that you can totally skip any hero that is not either providing an important upgrade to:
- All heroes' DPS
- All gold collected
- Optionally, a skill you need (like the Dark Ritual, Energize and Reload)
Or who is significantly providing you with the most DPS.
Cid is never doing any of these. In effective idle play you can easily skip:
- The Masked Samurai
- The Great Forest Seer
- Sir George II
- Referi Jerator
- Ma Zhu
You could, as these skills are barely needed to make your optimal run time, skip:
On the other hand, in active play, some of Cid's ability and upgrades could be useful (only) at the start. His ability gives click damage, his upgrades only affect himself. Thus, ultimately click damage comes from a factor of DPS via the abilities on Treebeast, Ivan, The Fisherman, Betty, Mercedes, Sir George II, and Frostleaf. See also those heroes providing critical click upgrades.
If you're still at a level of play where ascending with 1-3 more souls makes any real difference to you, you will want to level Cid into the 2k, 4k, or 6k range. However if you really can hit the 6k range, you're probably at a level where ascending is giving you 80-90k souls. Those couple of souls from hero levels are negligible.
Always do an optimal run with a clickable left unclicked before ascending, and you can click it to carry enough coin with you to pay for a Shinatobe, Grant, Frostleaf, or greater. They will basically carry you to level 260+ by themselves.
Note: This likely has to do with my ancients, not simply the fact I carry a clickable through ascension. EG I have Dogcog:25. for half cost heroes, and Iris:175 for at starting level 176, which I think factors into the highest unlocked level that determines the value of the clickable, then I have Mammon:410 giving +2050% gold. I'm not sure that Libertas:395 factors in because the +6465% gold is "gained from monsters when idle" and clickables aren't monsters.
It's well worth it for me though as all that gives me a value of 1.019e35 for the clickable totally outweighing the 1e8 for having Kleptos:30. This value allows me to right away buy:
Frostleaf:100, and 200 of everything below, plus all the available upgrade, activate metal detector and an energized dark ritual with reload... all of which will run close to optimally to level 265 (Again I do skip 2-175) before I have to or can buy any Dread Knight. 100 of those can run to about level 415 easily enough.
You can see my screenshots of an ascension: