Actually, in my previous job we were working with a custom board design with altium and other team with altera tools. The other team didn't find the IP for VGA monitor and SPI bus and we at the "altium" team did that very easily with the integrated IP, we had the solution effortlessly and worked really good. That caught my attention and make me fall in love with altium because along with the SCH/PCB design we were able to design also the FPGA part. As I'm starting I don't have thousandths of dollars to spend on IP and that is why the Altium approach seems appealing.
FPGA guy and Altium user here.
I'm not sure what sort of IP you're using in your designs, but VGA and SPI are trivial, and I wouldn't even bother looking for someone else's "IP Core." Rather than trying to adapt someone else's core, you can write your own, and make it meet your needs exactly, instead of having something that has a ton of generics and such to make it, well, generic.
And it's great fun having to implement, say, a Wishbone or other wacky bus master to talk to that open-source SPI core. I mean, extra work, right?
There seems to be this notion that FPGA design should be reduced to picking IP cores out of a catalog and placing them into a design. I'm sure the FPGA vendors like that approach, because they can sell chips to the non-FPGA folks. None of my designs have been this sort of cookie-cutter thing, and I'm sure I'm not the exception.
Count me as one of the many FPGA guys who looked at Altium's FPGA tools and asked, "Why bother?" There are better text editors than Altium's. You need to use the vendor synthesis and place-and-route tools. Nobody does a schematic top-level with HDL lower-level entities, so that excuse to use Altium's tools for FPGAs goes away.
And why bother indeed, especially when using those tools ties up a license that someone else could otherwise use for schematic capture and layout?
It was a solution in search of a problem.