It has been some time since I last played the game but I like the changes, well done.
I think the biggest imbalance currently is with perks and exp.
Perks: A girl can only do one job at a time. If you do a specialisation you will have around 4-6 perks (?) until the girl excells at a specific job and is 'maxed out'. So I don't see gaining more (all) perks breaking the game in any way. To serve customers you're supposed to excell in different jobs as well as you need to gain the corresponding stats. With the different health costs in the Inn you're also rotating girls around quite a lot.
If you want to make a balanced game you will need around the same amount of perks for every job. Currently the last 4 stats are missing a daily job. That would need to be fixed. Next bartending and maintance each have a 'super perk' that significantly increase the chance to gain a skillpoint while all others are missing something similar. Last but not least, there is a large difference between health regeneration and the amount of health you loose with adventures or while serving customers. So a few perks or a mechanic that balances health loss/gain would be recommended.
Exp: Currently you need to invest exp in the last 4 stats as they are missing a corresponding daily job. That makes exp cost skyrocket pretty fast. In addition, the double exp need for a new perk is a bottomless hole in the long run as well. At some point doing a job that brings your serving skill from 50 to 51 is way more worth than gaining exp from a customer you later invest to increase that skill. Why go for 3 fame and 13 exp with a 50 health loss when you can get an equivalent of 50 exp with the same time investment? Perhaps you can introduce a different calculation method after gaining a specific amount of perks? After requiring around 320 exp for a new perk farming and pushing gets more and more tedious.
As a perfectionist I try to unlock all portraits in the gallery. As the picture you get is calculated randomly that can take ages. How about being able to purchase/unlock them with money? I currently don't have anything better to do with my money anyway...
I'm looking forward on how things continue. Keep up the good work!
Actually the success in adventures is calculated by 2 skills. One of the last 4 and 1 of the 4 that can be raised by jobs. For instance, Success on a goblin adventure is calculated by both Adventuring and Serving. Furthermore the specialization is actually a problem, because in order to achieve the items you need to complete the quest you need to adventure to the point where all 4 factions are in their lairs.
This is complicated by the fact that with the 80 pt health drain you can only send a girl on an adventure once. Then you have to wait 4 days until she can adventure again. Meanwhile, the monster will move back to its' initial position if an adventure isn't undertaken and succeeded on the subsequent day, thereby resetting progress.
So, under the current structure if you send a girl once every 5 days you'll never complete the adventure. You have to send 4 girls consecutively which means you need 4 girls who are experts at everything.
The easiest fix would be to have the alchemist sell potions that you could use to restore the girls' health without resting or a way to increase max stamina above 100.
The perks system does need to be looked at as there are still perks that are just functionally much worse than others.
Your other point about the xp gain vs stamina drain when serving customers is dead on. Currently there are only 2 customers that are worth the investment as they give over 50xp. All the others are not worth it. There's a third that gives about 25 xp which makes it marginally equal to having a girl study. (gold gain instead of loss, fame gain, but 50 health loss (49 with Well, Well, Well perk) vs 30 health loss (29 WWW). Currently the best xp gain to health loss ratio is by far Cooking with Flirty Fry, WWW and Smarty pants as well as having the player intelligence perk (4-5xp for 2 health).
On a side note, while talking about WWW, it's an ok perk but really only useful at the beginning with Cleaning, Cooking and Serving, It becomes mostly useless with dancing, studying, servicing customers and adventuring. It could be vastly improved by making it a proportional health cost decrease. i.e. 1 point for cooking and cleaning, 2 for serving, 3 for dancing, 5 for study, 10 for prostitution and 20 for adventuring for instance. Either that or create a second perk that WWW is the pre-requisite for and that modifies the health loss to being proportional instead of static.
Edit: Grammar
Re-Edit: More thoughts.