islan, I purposely decided to wait a while before answering your initial post. Figuring that other would chime in and they have.
If I may, it seems that part of trouble that you are having with HARP comes from the mindset with which you approached the game. It seems (and obviously I could be wrong here), that you came to HARP with the mindset that it would work much on the same principles that D&D did. That higher versions of something was ALWAYS going to be a benefit.
That better armor was always going to be better than lesser armors in all ways. That scaling up a spell would always mean more damage, etc...
Sorry, but that is not the case. HARP is more of a game of potentials than absolutes.
You have to keep in mind that characters will continue to better their skills. This means that lower level character will use the lesser armors and move up as they get more skilled in moving in armor. Of course, their OBs are going up as well, and this increases their potential DBs overall. The actual increases are small overall, but the potentials continue to rise.
Elemental Bolts - yes, you get a minus to casting when you scale up, but your scaling up for the potential to do more damage. There is not, and
never will be a guarantee that you will do more damage when you scale something up.
You don't scale? You max out at 80 on the crit table, no matter how well you roll. You scale up one level, you can now max out at 90. But you don't know what you will roll when you do that, so you take a chance. However, when you make any attack, regardless of scaling, you don't know IF you will hit or how well you will do when you declare the attack. Scaling up a spell does not change that.
In D&D, you knew that IF you hit, you would do x dice of damage. And you had 2 different rolls to determine that. In HARP, how much damage you do is determined by how well you hit. By scaling up a spell you create the potential to hit better overall.
If you are coming from D&D, you might want to check out the Damage Dice option (HARPer's Bazaar #4) as it is actually something of a middle ground between HARPs crit tables and D&D's damage rules. Using this option, when you scale up an attack, you actually increase the dice size rolled to determine damage. (i.e. tiny = d6; small = d8, etc..). This might be a good way for you to start out.
Clerics -- clerics ignoring armor for casting spells is a D&Dism (and to some extent a RMism as well). However, (as one person pointed out) Clerics are pretty much expected to have a Holy Symbol, which includes a PP Adder that can offset penalties from scaling and armor (PP from an Adder are subtracted from the total needed for the spell, and then penalties for spending more than base cost in PP are determined). Another person pointed out that the Paladin (HARPer's Bazaar #2) has an ability that gives some benefit in this direction as well.
Healing spells -- ICE wanted healing kept simple. The name of the game is
High Adventure Role Playing. Notice the bolded words.
Having a detailed healing system kinda goes against the style of play. hehe. However, keep in mind that when you scale up a spell, you are going to end up taking longer to cast it...
Checks and balances.... That is another aspect of HARP. I tried to make sure that things were roughyl balanced across the board. This meant that heavy armor wasn't always your best option, but that it did have some benefits over lighter armors in some cases, and in other cases, lighter armors had more benefits. If that weren't the case, every fighter would be a tank.
Now it is quite possible that HARP isn't for you, and there is absolutely nothing wrong with that. You were at least open-minded enough to give it a try (there are some who won't try it cause it ain't d20 or it ain't the Indie game of the month, or whatever).
So, you definitely have my thanks for giving it a shot at least....
One more thing.... When you get behind that GM screen, it is YOUR game. It isn't my game, it isn't ICE's game, it is YOUR game. If you find something in the rules that you don't like, I fully expect you to change it!
If the rules do not mesh perfectly with your setting, change the rules, not your setting. That was one of my few issues with D&D. It came across as "do it our way or you are wrong". I saw way too many "RAW" discussions on EN World when I hung out there. For HARP, the "RAW" (Rules As Written) are your starting point. You are expected to adjust them to suit you and your setting. And if you get stumped on how to make something work for your setting, Post here and all of these wonderful people will chime in with loads of advice and ideas.
There is no real right or wrong way. If YOU and your group are having fun, then you are doing it right, end of story.