This is actually my master plan haha. I am eventually going to replace the 29 once I get a better handle on these planted tanks with a 90P (or something like this) is my secret goal.
So right I am going to replace the spec with either a 12 gal long or something smaller. I'm just replacing the spec first.
Do you think a 60p and a 29gal will be too redundant?
When laying out the 29 it did feel a weird dimension.
The top sounds like a plan. And again, you can spend about 1/10 of the cost in the short run and get a 40b, everything else can swap over to the 90P once you are ready.
As for the 60P and a 29 being too redundant...if you keep both, probably. I will be honest and say that the 60P is probably the worst dimensions from ADA in terms of a natural style tank. I was planning on doing a dutch tank before I got mine and was not sure if I was going to keep the 20 long I had or get another 29. Picture the 60p as similar to the 29 but add 3in more depth. Then they would almost be the same tank, the 29 being scaled up 1.25x. The extra 3 inch would do a lot for a 29, so the 60P is perfect for what I am doing. But, I think it would be a more "universal" tank at 24x12x12 or even better at 24x14x14.
I would say the 60P is a good replacement for the 29 though, if you don't mind going down. It's dimensions are better, it's a better tank, etc.
As per replacing the spec, it's actually not a bad size IMO but if you really want something different, a 12 long give you many options. There are other options that are closer to the dimensions of the spec to consider as well, just more high end. I think a Truaqua 8.6 would work, not sure if I have seen one in person. I am wondering if All About Fish may be able to order. Off the top of my head, almost seems like a small 60P just visualizing the dimensions. But, if you want to go with something more unique, the 12 gallon long is a size that works very well and can look way bigger than it is.