I use the same approach as you do ... with the corner of the drum towards me. My reasoning is that the natural angle of the hands (pointing in) will position themselves perpendicular to the two sides ... just as you diagram shows.

I have the Cajongas ... which is three drum set-up. I position them in a triangle formation ... which allows me to continue with the same approach as if I had only one drum.

Nice topic!

Good questions.

When I play traditional congas, they are typically lined up straight across. I have the option to do this with the cajongas ... via velcro strips, but seem to like the triangle set-up better. The latter method allows me to tilt ALL the drums ... which is important since they aren't very tall to begin with.

As far as using the traditional "rocking motion" or heel/finger technique ... like on congas, I position it up and away to allow plenty of room for the other hand.

Here's the deal ... you have to adapt your technique to the individual drum. If the smallest drum is 10 inch diameter ... you should have no problem using the heel/finger technique ... as traditional quintos are that small. If you feel it's too small ... take the bongo approach which uses the thumb (rather than the heel) and finger tips (rather than the full fingers).

It's kind of like finding the right size hammer for the nail you are using. You don't need a sledge hammer to drive a 1 penny nail. In the same instance, you won't benefit by trying to use heel/finger technique on the macho drum (small drum) on the bongos because your entire hand is bigger than the drum itself.

You may want to try pulling your hand back to play the "open" tones ... and not go so far into the center of the drum. This is the same technique I use with congas. Not only do I get a great sound, but I have less horizontal motion, which allows me to play faster! With my cajongas, I don't get a great "open" tone when I'm so far into the center.

It's hard for us to really know what the other is doing when we only have words ... and we can't physically see. Follow your ears and do what sounds best ... but be open to experiment.

Well, there is no hole.
There are 4 sides, top "membrane" and no bottom, like on conga.
But there are 2-3cm high rubbet feet beneath drums, so the air can escape.
I usualy tilt the smallest drum, other are positioned on feet.

Yes, in the near future I will also try wooden bongos, for now congas and cajon suffice .

Ales