I cant help you on the combo... but when we built our house my wife wanted to ensure the master bath had a tub instead of just a shower, she didn't want any jets either because they're a bear to clean and all that, so she opted for a garden tub I call it, sits at a 45 degree angle with a back surround and a custom cabinet across the front, it's at least 6 feet end to end and it's like filling my tender truck when she goes to get in it every day.. so I can say that.. she's used the thing almost every single day in the last three 3 1/2 years... My water bill can prove it!  I'm 6'2" and I was easily comfortable in the few times I've been in it, I just prefer to get in my shower and get out.  I am glad we kept them separate though, but I understand on a remodel space may be a limiting factor there.  My kids' bathroom has a combo, and it seems small to me, but then again, they're kids and I'm not the one using it!