I don’t drink milk but my wife does occasionally go for a cappuccino
Just highlighting this.... If you are only making the occasional cappuccino, a single boiler will be fine. Dual boiler machines are great! But it is a feature that doesnt match your needs. Allocate the money towards a better single boiler
On PIDs, since they have been raised, they are a nice feature but not one that becomes the difference between a good coffee and a bad coffee. Again, skipping this feature may save you money (better grinder?).
There are so many variables in the coffee world, it certainly feels like jumping into straight razor shaving like I did a few months ago.
I think you and I would get along! This is part of the reason I suggest E61. If you really want to play around and explore the space, there tend to be quite a few products for these machines (and even mods/hacks). On the other hand, if you just want to learn to make a decent a coffee with the machine you have (and not decent into madness; aka coffeegeek.com
)*, then a basic E61 machine without bells and whistles will serve you very well.
My utilitarian take on it is: with any good E61 (basic or fancy), the biggest variables affecting the quality of a shot are the grind settings and how you packed the portafilter. Inconsistencies created by the machines do exist but they arent the primary source of variance. You are. And trust me, there is a wide range of grind settings and ways you can pack a portafilter that make a really, really nice coffee. The system isn't that fragile and it isn't hard to find a good spot. All the bells and whistles (expense) and obsession (time) make it easier for you to repeatably make the so called 'god shot'. But that doesn't mean all the other shots are 'bad' in anyway!
Point being; I think a well-built, single boiler E61 without bells and whistles, paired with a stepless/micro adjustment grinder will offer you plenty of variables to play with. It will be capable of making truly excellent coffee and be your cheapest entry into the high-quality bracket.
* surely somebody out there on coffeegeek.com is saying "look, if you want a decent knive that cuts well without being obsessive about it"