I'll repost some of the reasons why the present character limit is a serious issue for some forums (taken from the XF2 demo site before it vanishes) and why increasing it in the upcoming XF2 would be an advance:
Let's take a random example of a list of topics from a forum dedicated to academics:
- Description of Markets, Optimising Tools and Cost-effective IT Solutions for the Balancing System (97)
- Dimensionless Numbers Used to Characterize Stratification in Water Tanks for Discharging at Low Flow Rates (106)
- The Effectiveness of Storage and Relocation Options in Renewable Energy Systems (79)
- Thermal Energy Storage: Systems and Applications (48)
- A Model to Design and Optimize Multi-energy Systems in Buildings at the Design Concept Stage (92)
- Thermal Stratification within the Water Tank (44)
- Exploration of Economical Sizing of Gas Engine ant Thermal Store for Combined Heat and Power Plants in the UK (109)
- The Case Study as a Research Method (35)
- The New German CHP Law – Criteria and Expectations (50)
- Twostep Decision and Optimisation Model for Centralised or Decentralised Thermal Storage in DH & C Systems (106)
- Thermodynamic and Economic Analysis of Heat Storage Application in Co-generation Systems (88)
- Optimal Design of Small CHP Plants in a Market with Fluctuating Electricity Prices (82)
- Constructing Load Profiles for Household Electricity and Hot Water from Time-use Data – Modelling Approach and Validation (121)
- Case Study: A Strategic Research Methodology (44)
- Controlling Micro-CHP Systems to Modulate Electrical Load Profiles (66)
- Exergy Methods for Assessing and Comparing Thermal Storage System (65)
- Renewable Energy: Its Physics, Engineering, Use, Environmental Impacts, Economy and Planning Aspects (100)
- Feasibility of CHP-plants with Thermal Stores in the German Spot Market (71)
- Multiple Criteria Assessment of Alternatives for Built and Human Environment Renovation (87)
As you can see, titles longer than 100 characters is a fact of life in some areas of interest, and not a rare one.
Also, the English language should not be taken for a standard here because there are languages that tend to empoy more characters. That is to say, 100 characters in English may be an equivalent of 120 characters in another language.
Overall, 200 characters would be a pretty safe bet (I'm talking here from experience of working with long titles in different languages).
It does not mean users are forced to use that many. But, please, allow to do so if there is a need!
Why not increase those limits and make them definable via ACP just like you have it with messages (i.e. ACP > Home > Options > Messages > Maximum Message Length)?